{"success":true,"version":"v1","request":{"tool":"list_calculators","category":null},"result":{"entity_type":"calculator_list","status":"completed","count":184,"calculators":[{"calculator_id":"compound-interest","entity_type":"calculator","name":"Compound Interest Calculator","category":"finance","tool_name":"calculate_compound_interest","description":"Computes the future balance of a principal earning compound interest at a chosen compounding frequency, optionally with a fixed deposit at the end of every month, and splits the result into contributions and interest.","use_when":"You need to project a savings account, certificate of deposit or investment balance from a starting amount, an annual rate, a term and optional monthly deposits.","do_not_use_when":"Interest is not reinvested (use simple-interest), you need the deposit required to hit a target (use savings-goal), or you are repaying a loan (use 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need the level payment of an amortizing loan (use loan-payment).","required_inputs":["principal","annual_rate_percent","years"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/simple-interest","markdown":"https://tttkmbb.com/finance/simple-interest.md","schema":"https://tttkmbb.com/api/v1/calculators/simple-interest","api":"https://tttkmbb.com/api/v1/calculate/simple-interest"}},{"calculator_id":"loan-payment","entity_type":"calculator","name":"Loan Payment Calculator","category":"finance","tool_name":"calculate_loan_payment","description":"Computes the level monthly payment of a fully amortizing fixed-rate loan from principal, annual rate and term, plus the total paid and total interest over the life of the loan.","use_when":"You need the monthly payment or total interest cost of an auto, personal, student or other fixed-rate installment loan given its amount, APR and term.","do_not_use_when":"You need property tax, insurance and HOA in the payment (use mortgage-payment), or you know the payment and want the payoff time (use debt-payoff).","required_inputs":["principal","annual_rate_percent"],"optional_inputs":["term_years","term_months"],"urls":{"html":"https://tttkmbb.com/finance/loan-payment","markdown":"https://tttkmbb.com/finance/loan-payment.md","schema":"https://tttkmbb.com/api/v1/calculators/loan-payment","api":"https://tttkmbb.com/api/v1/calculate/loan-payment"}},{"calculator_id":"mortgage-payment","entity_type":"calculator","name":"Mortgage Payment Calculator","category":"finance","tool_name":"calculate_mortgage_payment","description":"Computes the monthly principal-and-interest payment of a fixed-rate mortgage from home price, down payment, rate and term, then adds property tax, home insurance and HOA dues to give the full monthly housing payment and lifetime interest.","use_when":"You want the monthly cost of buying a home with a fixed-rate mortgage, including escrowed taxes and insurance, or the total interest over the 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comparing investment options.","do_not_use_when":"Payments are monthly while interest compounds at another frequency (use compound-interest), or you need to discount a future amount to today (use present-value).","required_inputs":["present_value","annual_rate_percent","years"],"optional_inputs":["compounding_frequency","periodic_payment","payment_timing"],"urls":{"html":"https://tttkmbb.com/finance/future-value","markdown":"https://tttkmbb.com/finance/future-value.md","schema":"https://tttkmbb.com/api/v1/calculators/future-value","api":"https://tttkmbb.com/api/v1/calculate/future-value"}},{"calculator_id":"present-value","entity_type":"calculator","name":"Present Value Calculator","category":"finance","tool_name":"calculate_present_value","description":"Discounts a single future amount back to today's value at a constant annual rate and compounding frequency, and reports the discount factor and the amount of discount.","use_when":"You need to know what a future sum is worth today, e.g. to compare a lump sum now against a payment later, or to price a zero-coupon bond.","do_not_use_when":"You need the value of a stream of payments (use future-value for accumulation, or a dedicated annuity/NPV tool), or you want to grow money forward (use future-value).","required_inputs":["future_value","annual_rate_percent","years"],"optional_inputs":["compounding_frequency"],"urls":{"html":"https://tttkmbb.com/finance/present-value","markdown":"https://tttkmbb.com/finance/present-value.md","schema":"https://tttkmbb.com/api/v1/calculators/present-value","api":"https://tttkmbb.com/api/v1/calculate/present-value"}},{"calculator_id":"roi","entity_type":"calculator","name":"ROI Calculator","category":"finance","tool_name":"calculate_roi","description":"Computes the net gain and percentage return on investment from the amount invested and its final value, and the annualized (compound) return when the holding period in years is given.","use_when":"You want the total percentage return 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conversions between two calendar years (that requires a CPI table such as the BLS inflation calculator), or investment discounting (use present-value).","required_inputs":["amount","annual_inflation_percent","years"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/inflation","markdown":"https://tttkmbb.com/finance/inflation.md","schema":"https://tttkmbb.com/api/v1/calculators/inflation","api":"https://tttkmbb.com/api/v1/calculate/inflation"}},{"calculator_id":"tip","entity_type":"calculator","name":"Tip Calculator","category":"finance","tool_name":"calculate_tip","description":"Computes the tip from a bill amount and tip percentage, the total including tip, and the per-person share when the bill is split evenly.","use_when":"You need to add a gratuity to a restaurant, delivery or service bill and optionally divide the total among several people.","do_not_use_when":"People pay for different items or unequal shares (use bill-split), or you need to add sales tax rather than a tip (use sales-tax).","required_inputs":["bill_amount"],"optional_inputs":["tip_percent","split_between"],"urls":{"html":"https://tttkmbb.com/finance/tip","markdown":"https://tttkmbb.com/finance/tip.md","schema":"https://tttkmbb.com/api/v1/calculators/tip","api":"https://tttkmbb.com/api/v1/calculate/tip"}},{"calculator_id":"discount","entity_type":"calculator","name":"Discount Calculator","category":"finance","tool_name":"calculate_discount","description":"Computes the final price and amount saved after a percentage discount, an optional second discount applied to the reduced price, and optional sales tax on the result.","use_when":"You want the sale price after a percent-off promotion, the effective rate of two stacked discounts (e.g. 20 % off plus an extra 10 %), or the checkout price with tax.","do_not_use_when":"You know the original and sale prices and need the percentage off (use percentage-change), or the discount is a fixed amount rather than a percent (just subtract it).","required_inputs":["original_price","discount_percent"],"optional_inputs":["second_discount_percent","tax_percent"],"urls":{"html":"https://tttkmbb.com/finance/discount","markdown":"https://tttkmbb.com/finance/discount.md","schema":"https://tttkmbb.com/api/v1/calculators/discount","api":"https://tttkmbb.com/api/v1/calculate/discount"}},{"calculator_id":"sales-tax","entity_type":"calculator","name":"Sales Tax Calculator","category":"finance","tool_name":"calculate_sales_tax","description":"Adds sales tax at a given rate to a pre-tax price, or works backwards from a tax-inclusive total to the pre-tax price and the tax paid.","use_when":"You need the checkout total for a price and a combined state/local sales-tax rate, or want to know how much of a receipt total was tax.","do_not_use_when":"The tax is a value-added tax quoted as net/gross (use vat, which is the same arithmetic with VAT terminology), or you need the tax rate for a specific location (look it up first).","required_inputs":["amount","tax_rate_percent"],"optional_inputs":["mode"],"urls":{"html":"https://tttkmbb.com/finance/sales-tax","markdown":"https://tttkmbb.com/finance/sales-tax.md","schema":"https://tttkmbb.com/api/v1/calculators/sales-tax","api":"https://tttkmbb.com/api/v1/calculate/sales-tax"}},{"calculator_id":"vat","entity_type":"calculator","name":"VAT Calculator","category":"finance","tool_name":"calculate_vat","description":"Adds VAT at a given rate to a net price, or removes it from a gross (VAT-inclusive) price, returning net, VAT and gross amounts.","use_when":"You need the VAT-inclusive price for an invoice, or the net price and VAT portion of a gross amount, at a known rate such as 20 % (UK), 19 % (Germany) or 21 % (Netherlands).","do_not_use_when":"You are dealing with US sales tax terminology (use sales-tax; the arithmetic is identical), or with multiple rates on one invoice (compute each line separately).","required_inputs":["amount"],"optional_inputs":["vat_rate_percent","mode"],"urls":{"html":"https://tttkmbb.com/finance/vat","markdown":"https://tttkmbb.com/finance/vat.md","schema":"https://tttkmbb.com/api/v1/calculators/vat","api":"https://tttkmbb.com/api/v1/calculate/vat"}},{"calculator_id":"margin-markup","entity_type":"calculator","name":"Margin and Markup Calculator","category":"finance","tool_name":"calculate_margin_markup","description":"Computes profit, gross margin percentage and markup percentage from a unit cost and a selling price, or derives the selling price from cost plus a target margin or markup.","use_when":"You are pricing a product or service and need to convert between cost, price, margin (profit as % of price) and markup (profit as % of cost).","do_not_use_when":"You need the sales volume that covers fixed costs (use break-even) or the tax on the price (use sales-tax / vat).","required_inputs":["cost"],"optional_inputs":["price","margin_percent","markup_percent"],"urls":{"html":"https://tttkmbb.com/finance/margin-markup","markdown":"https://tttkmbb.com/finance/margin-markup.md","schema":"https://tttkmbb.com/api/v1/calculators/margin-markup","api":"https://tttkmbb.com/api/v1/calculate/margin-markup"}},{"calculator_id":"break-even","entity_type":"calculator","name":"Break-Even Calculator","category":"finance","tool_name":"calculate_break_even","description":"Computes the contribution margin per unit and the number of units and revenue required for total revenue to equal total costs (or to reach a target profit).","use_when":"You are planning a product, service or event and need to know how many units must be sold at a given price to cover fixed costs, or to earn a specific profit.","do_not_use_when":"Price or variable cost changes with volume (needs a stepwise or non-linear model), or you only need margin/markup on one unit (use margin-markup).","required_inputs":["fixed_costs","price_per_unit","variable_cost_per_unit"],"optional_inputs":["target_profit"],"urls":{"html":"https://tttkmbb.com/finance/break-even","markdown":"https://tttkmbb.com/finance/break-even.md","schema":"https://tttkmbb.com/api/v1/calculators/break-even","api":"https://tttkmbb.com/api/v1/calculate/break-even"}},{"calculator_id":"rule-of-72","entity_type":"calculator","name":"Rule of 72 Calculator","category":"finance","tool_name":"calculate_rule_of_72","description":"Estimates the doubling time of an amount growing at a fixed annual rate with the Rule of 72, and compares it with the exact result ln 2 / ln(1 + r) for annual compounding and ln 2 / r for continuous compounding.","use_when":"You want a quick mental-math estimate of how long money (or debt, or prices) takes to double at a given annual growth rate, plus the exact figure.","do_not_use_when":"You need the balance after a specific number of years (use compound-interest) or the rate implied by two values (use cagr).","required_inputs":["annual_rate_percent"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/rule-of-72","markdown":"https://tttkmbb.com/finance/rule-of-72.md","schema":"https://tttkmbb.com/api/v1/calculators/rule-of-72","api":"https://tttkmbb.com/api/v1/calculate/rule-of-72"}},{"calculator_id":"debt-payoff","entity_type":"calculator","name":"Debt Payoff Calculator","category":"finance","tool_name":"calculate_debt_payoff","description":"Computes how many months a fixed monthly payment takes to clear a balance charged a given APR with monthly compounding, plus the total interest paid and the size of the final payment.","use_when":"You know a credit-card, loan or other balance, its APR and what you can pay each month, and want the payoff date and interest cost.","do_not_use_when":"You know the term and need the required payment (use loan-payment), or the payment is a percentage of the balance that shrinks over time (minimum-payment schedules).","required_inputs":["balance","annual_rate_percent","monthly_payment"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/debt-payoff","markdown":"https://tttkmbb.com/finance/debt-payoff.md","schema":"https://tttkmbb.com/api/v1/calculators/debt-payoff","api":"https://tttkmbb.com/api/v1/calculate/debt-payoff"}},{"calculator_id":"salary-converter","entity_type":"calculator","name":"Salary Converter","category":"finance","tool_name":"convert_salary","description":"Converts a pay amount quoted per hour, day, week, two weeks, month or year into all the other periods, using the hours per week, days per week and paid weeks per year you specify.","use_when":"You need to compare an hourly wage with an annual salary, or see what a salary works out to per month, per week or per hour before tax.","do_not_use_when":"You need take-home pay after income tax and deductions, or overtime at a premium rate (multiply the extra hours by the premium separately).","required_inputs":["amount","period"],"optional_inputs":["hours_per_week","days_per_week","weeks_per_year"],"urls":{"html":"https://tttkmbb.com/finance/salary-converter","markdown":"https://tttkmbb.com/finance/salary-converter.md","schema":"https://tttkmbb.com/api/v1/calculators/salary-converter","api":"https://tttkmbb.com/api/v1/calculate/salary-converter"}},{"calculator_id":"bmi","entity_type":"calculator","name":"BMI Calculator","category":"health","tool_name":"calculate_bmi","description":"Computes body mass index (BMI) from weight and height and classifies it with the WHO adult categories, plus the healthy weight range for that height.","use_when":"You need an adult's BMI, its WHO/CDC weight category, or the weight range that corresponds to a normal BMI (18.5–24.9) for a given height.","do_not_use_when":"The person is under 20 years old (children need age- and sex-specific BMI percentiles), or you need body-fat percentage (use body-fat) or calorie needs (use bmr / tdee).","required_inputs":["weight_kg","height_cm"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/health/bmi","markdown":"https://tttkmbb.com/health/bmi.md","schema":"https://tttkmbb.com/api/v1/calculators/bmi","api":"https://tttkmbb.com/api/v1/calculate/bmi"}},{"calculator_id":"bmr","entity_type":"calculator","name":"BMR Calculator","category":"health","tool_name":"calculate_bmr","description":"Estimates basal metabolic rate (calories burned at complete rest per day) with the Mifflin-St Jeor equation, and also reports the revised Harris-Benedict estimate.","use_when":"You need resting daily calorie needs for an adult from sex, weight, height and age, as a base for diet or TDEE calculations.","do_not_use_when":"You need total daily calories including activity (use tdee), the person is a child, pregnant, or has very high muscle mass (use a body-fat based equation such as Katch-McArdle instead).","required_inputs":["sex","weight_kg","height_cm","age_years"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/health/bmr","markdown":"https://tttkmbb.com/health/bmr.md","schema":"https://tttkmbb.com/api/v1/calculators/bmr","api":"https://tttkmbb.com/api/v1/calculate/bmr"}},{"calculator_id":"tdee","entity_type":"calculator","name":"TDEE Calculator","category":"health","tool_name":"calculate_tdee","description":"Estimates total daily energy expenditure from Mifflin-St Jeor BMR and an activity level, and derives calorie targets for maintaining, losing or gaining weight.","use_when":"You need daily maintenance calories for an adult, or calorie targets for a mild/standard deficit or surplus.","do_not_use_when":"The person is a child, pregnant or breastfeeding, or you only need the resting rate (use bmr).","required_inputs":["sex","weight_kg","height_cm","age_years"],"optional_inputs":["activity_level"],"urls":{"html":"https://tttkmbb.com/health/tdee","markdown":"https://tttkmbb.com/health/tdee.md","schema":"https://tttkmbb.com/api/v1/calculators/tdee","api":"https://tttkmbb.com/api/v1/calculate/tdee"}},{"calculator_id":"body-fat","entity_type":"calculator","name":"Body Fat Calculator","category":"health","tool_name":"calculate_body_fat_percentage","description":"Estimates body-fat percentage from height and neck, waist (and hip for women) circumferences using the US Navy method, and classifies the result with ACE categories.","use_when":"You want a tape-measure estimate of body-fat percentage and fat/lean mass without calipers or a DEXA scan.","do_not_use_when":"High accuracy is required (DEXA, hydrostatic weighing or BIA are better), or the person is a child or pregnant.","required_inputs":["sex","height_cm","waist_cm","neck_cm"],"optional_inputs":["hip_cm","weight_kg"],"urls":{"html":"https://tttkmbb.com/health/body-fat","markdown":"https://tttkmbb.com/health/body-fat.md","schema":"https://tttkmbb.com/api/v1/calculators/body-fat","api":"https://tttkmbb.com/api/v1/calculate/body-fat"}},{"calculator_id":"ideal-weight","entity_type":"calculator","name":"Ideal Weight Calculator","category":"health","tool_name":"calculate_ideal_weight","description":"Computes ideal body weight from height and sex with the four common clinical formulas (Devine, Robinson, Miller, Hamwi) and the BMI 18.5–24.9 healthy range.","use_when":"You need a reference 'ideal' weight for an adult, e.g. for drug dosing (Devine) or general guidance, or the healthy weight range for a height.","do_not_use_when":"The person is under 18 or you need body-composition targets; the formulas are population averages, not individual prescriptions.","required_inputs":["sex","height_cm"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/health/ideal-weight","markdown":"https://tttkmbb.com/health/ideal-weight.md","schema":"https://tttkmbb.com/api/v1/calculators/ideal-weight","api":"https://tttkmbb.com/api/v1/calculate/ideal-weight"}},{"calculator_id":"water-intake","entity_type":"calculator","name":"Water Intake Calculator","category":"health","tool_name":"calculate_daily_water_intake","description":"Estimates daily drinking-water needs from body weight (35 ml per kg) plus an allowance for exercise time, reported in litres, millilitres and 240 ml cups.","use_when":"You want a practical daily fluid target for a healthy adult based on weight and activity.","do_not_use_when":"The person has kidney, heart or liver disease, is pregnant, or works in extreme heat; medical advice supersedes this rule of thumb.","required_inputs":["weight_kg"],"optional_inputs":["exercise_minutes_per_day"],"urls":{"html":"https://tttkmbb.com/health/water-intake","markdown":"https://tttkmbb.com/health/water-intake.md","schema":"https://tttkmbb.com/api/v1/calculators/water-intake","api":"https://tttkmbb.com/api/v1/calculate/water-intake"}},{"calculator_id":"calorie-deficit","entity_type":"calculator","name":"Calorie Deficit & Weight Loss Time Calculator","category":"health","tool_name":"calculate_calorie_deficit_timeline","description":"Converts a weight change goal into total energy and the number of days and weeks required at a given daily calorie deficit or surplus, using 7,700 kcal per kilogram of body fat.","use_when":"You know the current and target weight and a planned daily deficit (or surplus) and want a time estimate, or want the deficit needed to hit a date.","do_not_use_when":"You need a medically supervised plan, the target implies more than 1 kg/week loss, or the person is a child; metabolic adaptation makes long projections approximate.","required_inputs":["current_weight_kg","target_weight_kg"],"optional_inputs":["daily_deficit_kcal"],"urls":{"html":"https://tttkmbb.com/health/calorie-deficit","markdown":"https://tttkmbb.com/health/calorie-deficit.md","schema":"https://tttkmbb.com/api/v1/calculators/calorie-deficit","api":"https://tttkmbb.com/api/v1/calculate/calorie-deficit"}},{"calculator_id":"macros","entity_type":"calculator","name":"Macro Calculator","category":"health","tool_name":"calculate_macros","description":"Splits a daily calorie target into grams of protein, carbohydrate and fat using a preset ratio (balanced, low-carb, high-protein, keto) or custom percentages.","use_when":"You have a calorie target (from tdee) and want gram targets for each macronutrient.","do_not_use_when":"Medical diets (renal, diabetic, PKU) are involved; those need individualised prescriptions.","required_inputs":["calories_per_day"],"optional_inputs":["preset","protein_percent","carbs_percent","fat_percent"],"urls":{"html":"https://tttkmbb.com/health/macros","markdown":"https://tttkmbb.com/health/macros.md","schema":"https://tttkmbb.com/api/v1/calculators/macros","api":"https://tttkmbb.com/api/v1/calculate/macros"}},{"calculator_id":"heart-rate-zones","entity_type":"calculator","name":"Heart Rate Zone Calculator","category":"health","tool_name":"calculate_heart_rate_zones","description":"Estimates maximum heart rate from age (Tanaka or Fox formula) and computes the five training zones, using the Karvonen heart-rate-reserve method when resting heart rate is supplied.","use_when":"You need training heart-rate ranges (zones 1–5) for an adult from age, optionally refined by resting heart rate.","do_not_use_when":"The person takes heart-rate-limiting medication (e.g. beta blockers) or has a measured maximum heart rate from a test (use that instead of an age 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and takes precedence).","required_inputs":["last_period_date"],"optional_inputs":["cycle_length_days","as_of_date"],"urls":{"html":"https://tttkmbb.com/health/pregnancy-due-date","markdown":"https://tttkmbb.com/health/pregnancy-due-date.md","schema":"https://tttkmbb.com/api/v1/calculators/pregnancy-due-date","api":"https://tttkmbb.com/api/v1/calculate/pregnancy-due-date"}},{"calculator_id":"ovulation","entity_type":"calculator","name":"Ovulation Calculator","category":"health","tool_name":"calculate_ovulation_date","description":"Estimates the ovulation date, the six-day fertile window and the next period start from the first day of the last period and the average cycle length.","use_when":"You want to estimate the most fertile days of a regular menstrual cycle.","do_not_use_when":"Cycles vary by more than a few days, hormonal contraception is used, or you need contraception (calendar estimates are not reliable for preventing 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pregnant.","required_inputs":["waist_cm","height_cm"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/health/waist-to-height-ratio","markdown":"https://tttkmbb.com/health/waist-to-height-ratio.md","schema":"https://tttkmbb.com/api/v1/calculators/waist-to-height-ratio","api":"https://tttkmbb.com/api/v1/calculate/waist-to-height-ratio"}},{"calculator_id":"lean-body-mass","entity_type":"calculator","name":"Lean Body Mass Calculator","category":"health","tool_name":"calculate_lean_body_mass","description":"Estimates lean body mass (fat-free mass) from weight, height and sex with the Boer (1984), James (1976) and Hume (1966) formulas.","use_when":"You need fat-free mass for drug dosing, nutrition planning or as a body-composition reference without a scan.","do_not_use_when":"You have measured body-fat percentage (lean mass = weight × (1 − body fat) is then more accurate) or the person is a child.","required_inputs":["sex","weight_kg","height_cm"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/health/lean-body-mass","markdown":"https://tttkmbb.com/health/lean-body-mass.md","schema":"https://tttkmbb.com/api/v1/calculators/lean-body-mass","api":"https://tttkmbb.com/api/v1/calculate/lean-body-mass"}},{"calculator_id":"protein-intake","entity_type":"calculator","name":"Protein Intake Calculator","category":"health","tool_name":"calculate_protein_intake","description":"Recommends a daily protein range in grams from body weight and goal (sedentary RDA 0.8 g/kg up to 1.6–2.2 g/kg for muscle gain or fat loss), based on the ISSN position stand.","use_when":"You want a protein target in grams per day for an adult given their activity or goal.","do_not_use_when":"Kidney disease or other medical conditions limit protein; consult a clinician.","required_inputs":["weight_kg"],"optional_inputs":["goal"],"urls":{"html":"https://tttkmbb.com/health/protein-intake","markdown":"https://tttkmbb.com/health/protein-intake.md","schema":"https://tttkmbb.com/api/v1/calculators/protein-intake","api":"https://tttkmbb.com/api/v1/calculate/protein-intake"}},{"calculator_id":"blood-pressure","entity_type":"calculator","name":"Blood Pressure Category Calculator","category":"health","tool_name":"classify_blood_pressure","description":"Classifies a systolic/diastolic blood pressure reading into the ACC/AHA 2017 categories (normal, elevated, stage 1, stage 2, hypertensive crisis) and reports mean arterial and pulse pressure.","use_when":"You have a resting blood-pressure reading and want the standard adult category plus MAP and pulse pressure.","do_not_use_when":"Diagnosing hypertension (requires repeated readings over time) or for children and pregnant women, who use different 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training percentages without attempting a true single-rep maximum.","do_not_use_when":"The set was more than 12 repetitions (prediction error grows quickly) or was not taken close to failure; use a heavier, lower-rep set instead.","required_inputs":["weight_lifted","reps"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/fitness/one-rep-max","markdown":"https://tttkmbb.com/fitness/one-rep-max.md","schema":"https://tttkmbb.com/api/v1/calculators/one-rep-max","api":"https://tttkmbb.com/api/v1/calculate/one-rep-max"}},{"calculator_id":"vo2-max","entity_type":"calculator","name":"VO2 Max Calculator","category":"fitness","tool_name":"estimate_vo2_max","description":"Estimates maximal oxygen uptake (VO2max, ml/kg/min) from the distance covered in the Cooper 12-minute run test, and/or from the ratio of maximum to resting heart rate (Uth et al. 2004).","use_when":"You have a 12-minute run distance or resting and maximum heart rates and want a field estimate of aerobic fitness.","do_not_use_when":"A laboratory or wearable-measured VO2max is available, or the person cannot run continuously for 12 minutes; the heart-rate method also requires a true (measured) maximum heart rate.","required_inputs":[],"optional_inputs":["distance_m","resting_heart_rate","max_heart_rate"],"urls":{"html":"https://tttkmbb.com/fitness/vo2-max","markdown":"https://tttkmbb.com/fitness/vo2-max.md","schema":"https://tttkmbb.com/api/v1/calculators/vo2-max","api":"https://tttkmbb.com/api/v1/calculate/vo2-max"}},{"calculator_id":"steps-to-distance","entity_type":"calculator","name":"Steps to Distance Calculator","category":"fitness","tool_name":"convert_steps_to_distance","description":"Converts a pedometer step count into distance using a measured stride length, or a walking stride estimated from height (stride ≈ 0.414 × height).","use_when":"You have a daily step count and want to know the distance walked in kilometres and miles, or the number of steps in a kilometre or 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targets.","do_not_use_when":"The distance is in yards (convert first: 1 yd = 0.9144 m) or you need running/cycling pace (use running-pace or pace-converter).","required_inputs":["distance_m","time"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/fitness/swim-pace","markdown":"https://tttkmbb.com/fitness/swim-pace.md","schema":"https://tttkmbb.com/api/v1/calculators/swim-pace","api":"https://tttkmbb.com/api/v1/calculate/swim-pace"}},{"calculator_id":"pace-converter","entity_type":"calculator","name":"Pace Converter","category":"fitness","tool_name":"convert_running_pace","description":"Converts a running pace or speed given in any one of min/km, min/mile, km/h or mph into all four units, plus seconds per km/mile and metres per second.","use_when":"You need to translate a treadmill speed into a pace, a min/mile pace into min/km, or any other pace/speed unit conversion.","do_not_use_when":"You have a distance and time rather than a pace (use running-pace) or a swim time (use swim-pace).","required_inputs":[],"optional_inputs":["pace_min_per_km","pace_min_per_mile","speed_kmh","speed_mph"],"urls":{"html":"https://tttkmbb.com/fitness/pace-converter","markdown":"https://tttkmbb.com/fitness/pace-converter.md","schema":"https://tttkmbb.com/api/v1/calculators/pace-converter","api":"https://tttkmbb.com/api/v1/calculate/pace-converter"}},{"calculator_id":"percentage","entity_type":"calculator","name":"Percentage Calculator","category":"math","tool_name":"calculate_percentage","description":"Solves the three basic percentage questions (a percentage of a number, what percentage one number is of another, and the whole behind a known part and percentage). Always returns the part, the whole and the percent.","use_when":"You need a percentage of a value, the percentage one value represents of another, or the base value that a part and its percentage imply.","do_not_use_when":"You need the percentage change between two values (use percentage-change), a price after a percentage discount (use discount) or a tax amount (use sales-tax).","required_inputs":["x","y"],"optional_inputs":["mode"],"urls":{"html":"https://tttkmbb.com/math/percentage","markdown":"https://tttkmbb.com/math/percentage.md","schema":"https://tttkmbb.com/api/v1/calculators/percentage","api":"https://tttkmbb.com/api/v1/calculate/percentage"}},{"calculator_id":"percentage-change","entity_type":"calculator","name":"Percentage Change Calculator","category":"math","tool_name":"calculate_percentage_change","description":"Computes the relative change from an old value to a new value as a percentage, the signed absolute change, the new/old ratio and the symmetric percent difference.","use_when":"You have a starting and an ending value and need the percentage increase or decrease, or a symmetric percent difference between two comparable values.","do_not_use_when":"You need a percentage of a number (use percentage), an annualised growth rate over several years (use cagr) or an investment return (use roi).","required_inputs":["old_value","new_value"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/percentage-change","markdown":"https://tttkmbb.com/math/percentage-change.md","schema":"https://tttkmbb.com/api/v1/calculators/percentage-change","api":"https://tttkmbb.com/api/v1/calculate/percentage-change"}},{"calculator_id":"quadratic-equation","entity_type":"calculator","name":"Quadratic Equation Solver","category":"math","tool_name":"solve_quadratic_equation","description":"Solves ax² + bx + c = 0 with the quadratic formula, reporting the discriminant, both roots (real, or complex conjugates written as strings), the vertex of the parabola and the sum and product of the roots.","use_when":"You need the solutions of a second-degree polynomial equation, or the vertex and discriminant of a parabola y = ax² + bx + c.","do_not_use_when":"The coefficient a is 0 (the equation is linear: x = −c / b), or you need roots of x^n = c for other powers (use nth-root).","required_inputs":["a","b","c"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/quadratic-equation","markdown":"https://tttkmbb.com/math/quadratic-equation.md","schema":"https://tttkmbb.com/api/v1/calculators/quadratic-equation","api":"https://tttkmbb.com/api/v1/calculate/quadratic-equation"}},{"calculator_id":"gcd-lcm","entity_type":"calculator","name":"GCD and LCM Calculator","category":"math","tool_name":"calculate_gcd_lcm","description":"Computes the greatest common divisor (highest common factor) and least common multiple of two or more integers with the Euclidean algorithm.","use_when":"You need the GCD/HCF or LCM of a list of integers, e.g. to reduce fractions, find a common denominator or check whether numbers are coprime.","do_not_use_when":"You need the prime factors themselves (use prime-factorization) or want to reduce a single fraction (use fraction-simplifier).","required_inputs":["numbers"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/gcd-lcm","markdown":"https://tttkmbb.com/math/gcd-lcm.md","schema":"https://tttkmbb.com/api/v1/calculators/gcd-lcm","api":"https://tttkmbb.com/api/v1/calculate/gcd-lcm"}},{"calculator_id":"prime-factorization","entity_type":"calculator","name":"Prime Factorization Calculator","category":"math","tool_name":"calculate_prime_factorization","description":"Decomposes an integer into its prime factors by trial division, tests primality, and derives the number and sum of its divisors from the exponents.","use_when":"You need the prime factors of an integer up to 10^12, want to know whether it is prime, or need its divisor count.","do_not_use_when":"You need the GCD or LCM of several numbers (use gcd-lcm) or factorials and binomial coefficients (use factorial, combinations-permutations).","required_inputs":["n"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/prime-factorization","markdown":"https://tttkmbb.com/math/prime-factorization.md","schema":"https://tttkmbb.com/api/v1/calculators/prime-factorization","api":"https://tttkmbb.com/api/v1/calculate/prime-factorization"}},{"calculator_id":"factorial","entity_type":"calculator","name":"Factorial Calculator","category":"math","tool_name":"calculate_factorial","description":"Computes n! = 1 × 2 × … × n for integers from 0 to 170, together with the number of decimal digits, the number of trailing zeros and a scientific-notation form.","use_when":"You need the factorial of an integer, e.g. for counting arrangements or as a building block of permutations and combinations.","do_not_use_when":"n exceeds 170 (the result overflows double precision; use Stirling's approximation or log-gamma) or you need C(n, k) / P(n, k) directly (use combinations-permutations).","required_inputs":["n"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/factorial","markdown":"https://tttkmbb.com/math/factorial.md","schema":"https://tttkmbb.com/api/v1/calculators/factorial","api":"https://tttkmbb.com/api/v1/calculate/factorial"}},{"calculator_id":"combinations-permutations","entity_type":"calculator","name":"Combinations and Permutations Calculator","category":"math","tool_name":"calculate_combinations_permutations","description":"Counts the ways to choose k items from n: combinations C(n, k) when order does not matter and permutations P(n, k) when it does, with or without repetition.","use_when":"You need nCr (binomial coefficient), nPr, or the number of multisets or sequences of length k drawn from n items.","do_not_use_when":"You need the probability of a specific outcome (use probability-of-events or binomial-distribution) or a plain factorial (use factorial).","required_inputs":["n","k"],"optional_inputs":["with_repetition"],"urls":{"html":"https://tttkmbb.com/math/combinations-permutations","markdown":"https://tttkmbb.com/math/combinations-permutations.md","schema":"https://tttkmbb.com/api/v1/calculators/combinations-permutations","api":"https://tttkmbb.com/api/v1/calculate/combinations-permutations"}},{"calculator_id":"exponent","entity_type":"calculator","name":"Exponent Calculator","category":"math","tool_name":"calculate_exponent","description":"Raises a base to any real exponent (base^exponent), including negative and fractional exponents, and reports the reciprocal and a scientific-notation form.","use_when":"You need a power such as 2^10, 1.05^30 or 8^(1/3), or a quick check of how large a power gets.","do_not_use_when":"You need the exponent that produces a given result (use logarithm) or the n-th root with sign handling for negatives (use nth-root).","required_inputs":["base","exponent"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/exponent","markdown":"https://tttkmbb.com/math/exponent.md","schema":"https://tttkmbb.com/api/v1/calculators/exponent","api":"https://tttkmbb.com/api/v1/calculate/exponent"}},{"calculator_id":"nth-root","entity_type":"calculator","name":"Nth Root Calculator","category":"math","tool_name":"calculate_nth_root","description":"Computes the principal n-th root of a number (value^(1/n)), returning the real negative root for odd n and the second, negative root for even n.","use_when":"You need √x, ∛x or any integer-degree root, including odd roots of negative numbers.","do_not_use_when":"You need a fractional power such as x^(2/3) (use exponent) or the solutions of a quadratic (use quadratic-equation).","required_inputs":["value","n"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/nth-root","markdown":"https://tttkmbb.com/math/nth-root.md","schema":"https://tttkmbb.com/api/v1/calculators/nth-root","api":"https://tttkmbb.com/api/v1/calculate/nth-root"}},{"calculator_id":"logarithm","entity_type":"calculator","name":"Logarithm Calculator","category":"math","tool_name":"calculate_logarithm","description":"Computes the logarithm of a positive number to any base using the change-of-base formula, and always reports the natural, common (base 10) and binary (base 2) logarithms.","use_when":"You need log_b(x) for an arbitrary base, or ln, log10 and log2 of a number at once.","do_not_use_when":"You need to raise a base to a power (use exponent) or a root (use nth-root); for pH-style −log10 of a concentration use ph.","required_inputs":["value"],"optional_inputs":["base"],"urls":{"html":"https://tttkmbb.com/math/logarithm","markdown":"https://tttkmbb.com/math/logarithm.md","schema":"https://tttkmbb.com/api/v1/calculators/logarithm","api":"https://tttkmbb.com/api/v1/calculate/logarithm"}},{"calculator_id":"fraction-simplifier","entity_type":"calculator","name":"Fraction Simplifier","category":"math","tool_name":"calculate_simplified_fraction","description":"Reduces a fraction to lowest terms by dividing by the GCD and converts it to a mixed number, a decimal and a percentage.","use_when":"You have a numerator and denominator and want the reduced fraction, its mixed-number form, decimal value or percent.","do_not_use_when":"You need to add or multiply fractions (reduce each result with this tool afterwards) or to simplify a ratio of non-integers (use ratio).","required_inputs":["numerator","denominator"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/fraction-simplifier","markdown":"https://tttkmbb.com/math/fraction-simplifier.md","schema":"https://tttkmbb.com/api/v1/calculators/fraction-simplifier","api":"https://tttkmbb.com/api/v1/calculate/fraction-simplifier"}},{"calculator_id":"ratio","entity_type":"calculator","name":"Ratio Calculator","category":"math","tool_name":"calculate_ratio","description":"Simplifies a ratio a:b to lowest terms (decimals are scaled to integers first), expresses it as a decimal, as n:1 and as percentage shares, and optionally scales it to a new value of a.","use_when":"You need to reduce a ratio, compare two quantities, or find the matching second value when the first is scaled (e.g. mixing or recipe ratios).","do_not_use_when":"You are solving a/b = c/x with three known values (use proportion) or reducing a fraction with sign handling (use fraction-simplifier).","required_inputs":["a","b"],"optional_inputs":["new_a"],"urls":{"html":"https://tttkmbb.com/math/ratio","markdown":"https://tttkmbb.com/math/ratio.md","schema":"https://tttkmbb.com/api/v1/calculators/ratio","api":"https://tttkmbb.com/api/v1/calculate/ratio"}},{"calculator_id":"proportion","entity_type":"calculator","name":"Proportion Calculator","category":"math","tool_name":"solve_proportion","description":"Solves the proportion a / b = c / x for the unknown fourth term by cross-multiplication (x = b × c / a) and reports the common scale factor.","use_when":"Three terms of a proportion are known and you need the fourth, e.g. converting a recipe, map scale or unit rate.","do_not_use_when":"You only want to simplify a ratio (use ratio) or the unknown is a percentage (use percentage).","required_inputs":["a","b","c"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/proportion","markdown":"https://tttkmbb.com/math/proportion.md","schema":"https://tttkmbb.com/api/v1/calculators/proportion","api":"https://tttkmbb.com/api/v1/calculate/proportion"}},{"calculator_id":"slope","entity_type":"calculator","name":"Slope Calculator","category":"math","tool_name":"calculate_slope","description":"Computes the slope of the line through two points (rise over run), its y- and x-intercepts, the slope-intercept equation y = mx + b, the angle of inclination and the distance between the points.","use_when":"You have two points and need the gradient or the equation of the line through them.","do_not_use_when":"You need a best-fit line through many points (use linear-regression) or only the distance between two points (use distance-2d).","required_inputs":["x1","y1","x2","y2"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/slope","markdown":"https://tttkmbb.com/math/slope.md","schema":"https://tttkmbb.com/api/v1/calculators/slope","api":"https://tttkmbb.com/api/v1/calculate/slope"}},{"calculator_id":"distance-2d","entity_type":"calculator","name":"Distance Between Two Points Calculator","category":"math","tool_name":"calculate_distance_2d","description":"Computes the straight-line (Euclidean) distance between two points in the plane, their midpoint, the coordinate differences and the Manhattan distance.","use_when":"You have two (x, y) coordinates and need the distance between them or the point halfway between them.","do_not_use_when":"You need the slope or equation of the line through the points (use slope) or the third side of a right triangle from two sides (use pythagorean).","required_inputs":["x1","y1","x2","y2"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/distance-2d","markdown":"https://tttkmbb.com/math/distance-2d.md","schema":"https://tttkmbb.com/api/v1/calculators/distance-2d","api":"https://tttkmbb.com/api/v1/calculate/distance-2d"}},{"calculator_id":"pythagorean","entity_type":"calculator","name":"Pythagorean Theorem Calculator","category":"math","tool_name":"solve_pythagorean_theorem","description":"Finds the missing side of a right triangle from any two of the legs a, b and hypotenuse c using a² + b² = c², and reports the area, perimeter and acute angles.","use_when":"You know two sides of a right triangle and need the third, or want to check whether three lengths form a right triangle.","do_not_use_when":"The triangle is not right-angled (use triangle-solver) or you need the distance between coordinates (use distance-2d).","required_inputs":[],"optional_inputs":["a","b","c"],"urls":{"html":"https://tttkmbb.com/math/pythagorean","markdown":"https://tttkmbb.com/math/pythagorean.md","schema":"https://tttkmbb.com/api/v1/calculators/pythagorean","api":"https://tttkmbb.com/api/v1/calculate/pythagorean"}},{"calculator_id":"rounding","entity_type":"calculator","name":"Rounding Calculator","category":"math","tool_name":"calculate_rounded_value","description":"Rounds a number to a given number of decimal places (negative for tens, hundreds, …) or significant figures using round-half-away-from-zero, and also reports the ceiling, floor and truncated values at the same precision.","use_when":"You need a number rounded to a fixed number of decimals or significant figures, or its ceiling/floor at that precision, with the exact decimal behaviour (2.675 → 2.68).","do_not_use_when":"You want a number written in scientific or engineering notation (use scientific-notation).","required_inputs":["value"],"optional_inputs":["precision","mode"],"urls":{"html":"https://tttkmbb.com/math/rounding","markdown":"https://tttkmbb.com/math/rounding.md","schema":"https://tttkmbb.com/api/v1/calculators/rounding","api":"https://tttkmbb.com/api/v1/calculate/rounding"}},{"calculator_id":"arithmetic-sequence","entity_type":"calculator","name":"Arithmetic Sequence Calculator","category":"math","tool_name":"calculate_arithmetic_sequence","description":"Computes the n-th term and the sum of the first n terms of an arithmetic progression from the first term and the common difference, and lists the first terms.","use_when":"Terms increase or decrease by a constant amount (e.g. 2, 5, 8, …) and you need a specific term or the total of the first n terms.","do_not_use_when":"Terms are multiplied by a constant ratio (use geometric-sequence) or you need interest that compounds (use compound-interest).","required_inputs":["first_term","common_difference","n"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/arithmetic-sequence","markdown":"https://tttkmbb.com/math/arithmetic-sequence.md","schema":"https://tttkmbb.com/api/v1/calculators/arithmetic-sequence","api":"https://tttkmbb.com/api/v1/calculate/arithmetic-sequence"}},{"calculator_id":"geometric-sequence","entity_type":"calculator","name":"Geometric Sequence Calculator","category":"math","tool_name":"calculate_geometric_sequence","description":"Computes the n-th term and the sum of the first n terms of a geometric progression from the first term and common ratio, plus the sum to infinity when |r| < 1.","use_when":"Each term is the previous one multiplied by a constant ratio (e.g. 3, 6, 12, …) and you need a term, a partial sum or the limit of the series.","do_not_use_when":"Terms change by a constant difference (use arithmetic-sequence) or you need a money value with periodic deposits (use future-value / compound-interest).","required_inputs":["first_term","common_ratio","n"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/geometric-sequence","markdown":"https://tttkmbb.com/math/geometric-sequence.md","schema":"https://tttkmbb.com/api/v1/calculators/geometric-sequence","api":"https://tttkmbb.com/api/v1/calculate/geometric-sequence"}},{"calculator_id":"modulo","entity_type":"calculator","name":"Modulo Calculator","category":"math","tool_name":"calculate_modulo","description":"Divides one number by another and reports the remainder under the three common sign conventions (truncated as in C/JavaScript, floored as in Python, and the non-negative Euclidean modulo) together with the integer quotient.","use_when":"You need a mod b, the remainder of a division, or want to know how different programming languages treat negative operands.","do_not_use_when":"You need the prime factors or divisors of a number (use prime-factorization) or a change of number base (use base-converter).","required_inputs":["dividend","divisor"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/modulo","markdown":"https://tttkmbb.com/math/modulo.md","schema":"https://tttkmbb.com/api/v1/calculators/modulo","api":"https://tttkmbb.com/api/v1/calculate/modulo"}},{"calculator_id":"base-converter","entity_type":"calculator","name":"Number Base Converter","category":"math","tool_name":"convert_number_base","description":"Converts an integer written in one base (2–36) to another, using exact arbitrary-precision arithmetic, and always shows the binary, octal, decimal and hexadecimal forms.","use_when":"You need to convert between binary, octal, decimal, hexadecimal or any positional base up to 36, including large integers.","do_not_use_when":"The value has a fractional part, you need Roman numerals (use roman-numeral) or byte/bit unit conversions (use data-storage).","required_inputs":["value"],"optional_inputs":["from_base","to_base"],"urls":{"html":"https://tttkmbb.com/math/base-converter","markdown":"https://tttkmbb.com/math/base-converter.md","schema":"https://tttkmbb.com/api/v1/calculators/base-converter","api":"https://tttkmbb.com/api/v1/calculate/base-converter"}},{"calculator_id":"scientific-notation","entity_type":"calculator","name":"Scientific Notation Converter","category":"math","tool_name":"convert_to_scientific_notation","description":"Writes a number in normalised scientific notation m × 10^e with 1 ≤ |m| < 10, in E-notation, and in engineering notation (exponent a multiple of 3).","use_when":"You need a very large or very small number in scientific or engineering form, or its order of magnitude.","do_not_use_when":"You want to round a number to a given precision (use rounding) or compute a power (use exponent).","required_inputs":["value"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/math/scientific-notation","markdown":"https://tttkmbb.com/math/scientific-notation.md","schema":"https://tttkmbb.com/api/v1/calculators/scientific-notation","api":"https://tttkmbb.com/api/v1/calculate/scientific-notation"}},{"calculator_id":"circle","entity_type":"calculator","name":"Circle Calculator","category":"geometry","tool_name":"calculate_circle_properties","description":"Computes the area, circumference, diameter and radius of a circle from either its radius or its diameter. 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Lengths are unit-agnostic; the area is in the square of the input unit.","use_when":"You need the area, perimeter or diagonal of a rectangle or square (enter equal length and width).","do_not_use_when":"The shape is a box with depth (use rectangular-prism) or a slanted quadrilateral (use parallelogram or trapezoid).","required_inputs":["length","width"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/rectangle","markdown":"https://tttkmbb.com/geometry/rectangle.md","schema":"https://tttkmbb.com/api/v1/calculators/rectangle","api":"https://tttkmbb.com/api/v1/calculate/rectangle"}},{"calculator_id":"trapezoid","entity_type":"calculator","name":"Trapezoid Calculator","category":"geometry","tool_name":"calculate_trapezoid_properties","description":"Computes the area and midsegment of a trapezoid (trapezium) from its two parallel sides and height, and the perimeter when both non-parallel legs are given.","use_when":"You need the area of a quadrilateral with exactly one pair of parallel sides, or its perimeter when all four sides are known.","do_not_use_when":"Both pairs of sides are parallel (use parallelogram or rectangle) or you only know the four sides without the height (the height cannot be derived without an angle in general).","required_inputs":["base_a","base_b","height"],"optional_inputs":["leg_c","leg_d"],"urls":{"html":"https://tttkmbb.com/geometry/trapezoid","markdown":"https://tttkmbb.com/geometry/trapezoid.md","schema":"https://tttkmbb.com/api/v1/calculators/trapezoid","api":"https://tttkmbb.com/api/v1/calculate/trapezoid"}},{"calculator_id":"parallelogram","entity_type":"calculator","name":"Parallelogram Calculator","category":"geometry","tool_name":"calculate_parallelogram_properties","description":"Computes the area of a parallelogram from base and height and, when the slanted side is given, its perimeter, the acute angle between base and side in degrees, and both diagonals.","use_when":"You need the area, perimeter, angles or diagonals of a quadrilateral whose opposite sides are parallel (including rhombi).","do_not_use_when":"All angles are right angles (use rectangle) or only one pair of sides is parallel (use trapezoid).","required_inputs":["base","height"],"optional_inputs":["side"],"urls":{"html":"https://tttkmbb.com/geometry/parallelogram","markdown":"https://tttkmbb.com/geometry/parallelogram.md","schema":"https://tttkmbb.com/api/v1/calculators/parallelogram","api":"https://tttkmbb.com/api/v1/calculate/parallelogram"}},{"calculator_id":"regular-polygon","entity_type":"calculator","name":"Regular Polygon Calculator","category":"geometry","tool_name":"calculate_regular_polygon_properties","description":"Computes the area, perimeter, interior and exterior angles in degrees, apothem, circumradius and number of diagonals of a regular polygon from its number of sides and side length.","use_when":"You need properties of an equilateral, equiangular polygon (pentagon, hexagon, octagon, …) with 3 to 100 sides.","do_not_use_when":"The polygon is irregular (split it into triangles and use triangle-area) or is a square, for which rectangle also works.","required_inputs":["number_of_sides","side_length"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/regular-polygon","markdown":"https://tttkmbb.com/geometry/regular-polygon.md","schema":"https://tttkmbb.com/api/v1/calculators/regular-polygon","api":"https://tttkmbb.com/api/v1/calculate/regular-polygon"}},{"calculator_id":"ellipse","entity_type":"calculator","name":"Ellipse Calculator","category":"geometry","tool_name":"calculate_ellipse_properties","description":"Computes the area, approximate perimeter (Ramanujan's second approximation), eccentricity and focal distances of an ellipse from its semi-major and semi-minor axes.","use_when":"You need the area or circumference of an ellipse or oval, or the position of its foci, from the two half-axes.","do_not_use_when":"Both axes are equal (use circle for exact results) or you need the arc length of part of an ellipse, which requires elliptic integrals.","required_inputs":["semi_major_a","semi_minor_b"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/ellipse","markdown":"https://tttkmbb.com/geometry/ellipse.md","schema":"https://tttkmbb.com/api/v1/calculators/ellipse","api":"https://tttkmbb.com/api/v1/calculate/ellipse"}},{"calculator_id":"sphere","entity_type":"calculator","name":"Sphere Calculator","category":"geometry","tool_name":"calculate_sphere_properties","description":"Computes the volume, surface area, diameter and great-circle circumference of a sphere from its radius. The volume is in the cube and the surface area in the square of the input unit.","use_when":"You need the volume or surface area of a ball, globe, bubble or planet from its radius.","do_not_use_when":"The object is a hemisphere or spherical cap (halve or use the cap formula), an ellipsoid, or you only need a flat circle (use circle).","required_inputs":["radius"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/sphere","markdown":"https://tttkmbb.com/geometry/sphere.md","schema":"https://tttkmbb.com/api/v1/calculators/sphere","api":"https://tttkmbb.com/api/v1/calculate/sphere"}},{"calculator_id":"cylinder","entity_type":"calculator","name":"Cylinder Calculator","category":"geometry","tool_name":"calculate_cylinder_properties","description":"Computes the volume, base area, lateral (curved) surface area and total surface area of a right circular cylinder from its radius and height.","use_when":"You need the capacity or surface of a can, tank, pipe, pillar or any straight circular cylinder.","do_not_use_when":"The cylinder is hollow (compute outer minus inner), tilted (oblique), or tapers to a point (use cone).","required_inputs":["radius","height"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/cylinder","markdown":"https://tttkmbb.com/geometry/cylinder.md","schema":"https://tttkmbb.com/api/v1/calculators/cylinder","api":"https://tttkmbb.com/api/v1/calculate/cylinder"}},{"calculator_id":"cone","entity_type":"calculator","name":"Cone Calculator","category":"geometry","tool_name":"calculate_cone_properties","description":"Computes the volume, slant height, base area, lateral (curved) surface area, total surface area and half-apex angle in degrees of a right circular cone from its base radius and height.","use_when":"You need the capacity or surface of a funnel, cone-shaped pile, roof or any right circular cone.","do_not_use_when":"The cone is truncated (frustum), oblique, or has a square base (use pyramid).","required_inputs":["radius","height"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/cone","markdown":"https://tttkmbb.com/geometry/cone.md","schema":"https://tttkmbb.com/api/v1/calculators/cone","api":"https://tttkmbb.com/api/v1/calculate/cone"}},{"calculator_id":"rectangular-prism","entity_type":"calculator","name":"Rectangular Prism Calculator","category":"geometry","tool_name":"calculate_rectangular_prism_properties","description":"Computes the volume, total surface area, space diagonal and total edge length of a rectangular prism (cuboid or box) from its length, width and height.","use_when":"You need the capacity, surface or longest internal dimension of a box, room, aquarium, container or any cuboid.","do_not_use_when":"The base is not a rectangle (use cylinder or pyramid) or you only need the floor area (use rectangle).","required_inputs":["length","width","height"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/rectangular-prism","markdown":"https://tttkmbb.com/geometry/rectangular-prism.md","schema":"https://tttkmbb.com/api/v1/calculators/rectangular-prism","api":"https://tttkmbb.com/api/v1/calculate/rectangular-prism"}},{"calculator_id":"pyramid","entity_type":"calculator","name":"Square Pyramid Calculator","category":"geometry","tool_name":"calculate_square_pyramid_properties","description":"Computes the volume, slant height, lateral edge, base area, lateral and total surface area and face slope in degrees of a right square pyramid from its base side and height.","use_when":"You need the volume or surface of a pyramid with a square base and the apex above the centre of the base.","do_not_use_when":"The base is a circle (use cone), a non-square rectangle or triangle, or the apex is off-centre (oblique pyramid).","required_inputs":["base_side","height"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/geometry/pyramid","markdown":"https://tttkmbb.com/geometry/pyramid.md","schema":"https://tttkmbb.com/api/v1/calculators/pyramid","api":"https://tttkmbb.com/api/v1/calculate/pyramid"}},{"calculator_id":"descriptive-statistics","entity_type":"calculator","name":"Descriptive Statistics Calculator","category":"statistics","tool_name":"calculate_descriptive_statistics","description":"Computes summary statistics for a list of numbers: count, sum, mean, median, mode, range, sample and population variance and standard deviation, standard error, coefficient of variation, quartiles (linear interpolation) and skewness.","use_when":"You have a set of numeric observations and need its central tendency, spread or quartiles, e.g. the standard deviation of a data set.","do_not_use_when":"You need a single percentile or the percentile rank of one value (use percentile), a standardised score (use z-score), or statistics of two paired variables (use correlation or linear-regression).","required_inputs":["values"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/statistics/descriptive-statistics","markdown":"https://tttkmbb.com/statistics/descriptive-statistics.md","schema":"https://tttkmbb.com/api/v1/calculators/descriptive-statistics","api":"https://tttkmbb.com/api/v1/calculate/descriptive-statistics"}},{"calculator_id":"z-score","entity_type":"calculator","name":"Z-Score Calculator","category":"statistics","tool_name":"calculate_z_score","description":"Standardises a value against a mean and standard deviation (z = (x − μ) / σ) and reports the corresponding percentile and tail probabilities under the normal distribution.","use_when":"You need how many standard deviations a value lies from the mean, or the percentile a value corresponds to in a normally distributed population (test scores, measurements, quality control).","do_not_use_when":"You need the probability between two values or the density (use normal-distribution), the data are clearly not normal, or you need the empirical percentile rank within an actual data set (use percentile).","required_inputs":["value","mean","std_dev"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/statistics/z-score","markdown":"https://tttkmbb.com/statistics/z-score.md","schema":"https://tttkmbb.com/api/v1/calculators/z-score","api":"https://tttkmbb.com/api/v1/calculate/z-score"}},{"calculator_id":"normal-distribution","entity_type":"calculator","name":"Normal Distribution Calculator","category":"statistics","tool_name":"calculate_normal_distribution_probability","description":"Computes cumulative probabilities P(X < x), P(X > x) and P(x < X < x2) and the density for a normal (Gaussian) distribution with a given mean and standard deviation.","use_when":"You need the probability that a normally distributed quantity falls below, above or between given values, or the z-scores of those values.","do_not_use_when":"The variable is a count of successes or events (use binomial-distribution or poisson-distribution), or you need the value at a given probability from real data (use percentile).","required_inputs":["x"],"optional_inputs":["mean","std_dev","x2"],"urls":{"html":"https://tttkmbb.com/statistics/normal-distribution","markdown":"https://tttkmbb.com/statistics/normal-distribution.md","schema":"https://tttkmbb.com/api/v1/calculators/normal-distribution","api":"https://tttkmbb.com/api/v1/calculate/normal-distribution"}},{"calculator_id":"confidence-interval","entity_type":"calculator","name":"Confidence Interval Calculator","category":"statistics","tool_name":"calculate_confidence_interval","description":"Computes a confidence interval for a population mean from the sample mean, standard deviation and sample size using the normal (z) critical value: mean ± z · s / √n.","use_when":"You have a sample mean, its standard deviation and the sample size and want the interval that likely contains the population mean at a given confidence level.","do_not_use_when":"The statistic is a proportion or survey percentage (use margin-of-error), or the sample is small (n < 30) with an unknown population SD, where a t-based interval is the correct choice and this z interval is slightly too narrow.","required_inputs":["sample_mean","std_dev","sample_size"],"optional_inputs":["confidence_level_percent"],"urls":{"html":"https://tttkmbb.com/statistics/confidence-interval","markdown":"https://tttkmbb.com/statistics/confidence-interval.md","schema":"https://tttkmbb.com/api/v1/calculators/confidence-interval","api":"https://tttkmbb.com/api/v1/calculate/confidence-interval"}},{"calculator_id":"sample-size","entity_type":"calculator","name":"Sample Size Calculator","category":"statistics","tool_name":"calculate_sample_size","description":"Computes the number of respondents needed to estimate a population proportion within a given margin of error at a given confidence level (Cochran's formula), with an optional finite population correction.","use_when":"You are planning a survey, poll or A/B test on a proportion and need to know how many people to sample for a target margin of error.","do_not_use_when":"You already have a sample and want its margin of error (use margin-of-error), or you are estimating a mean rather than a proportion (the formula would need the standard deviation instead of p(1 − p)).","required_inputs":["margin_of_error_percent"],"optional_inputs":["confidence_level_percent","expected_proportion_percent","population_size"],"urls":{"html":"https://tttkmbb.com/statistics/sample-size","markdown":"https://tttkmbb.com/statistics/sample-size.md","schema":"https://tttkmbb.com/api/v1/calculators/sample-size","api":"https://tttkmbb.com/api/v1/calculate/sample-size"}},{"calculator_id":"margin-of-error","entity_type":"calculator","name":"Margin of Error Calculator","category":"statistics","tool_name":"calculate_margin_of_error","description":"Computes the margin of error (half-width of the confidence interval) of a sample proportion from the sample size, confidence level and observed percentage, with an optional finite population correction.","use_when":"You have poll or survey results (n respondents, x % answering a certain way) and need the ± margin at a confidence level.","do_not_use_when":"You are still planning the survey and need the required sample size (use sample-size), or the statistic is a mean rather than a percentage (use confidence-interval).","required_inputs":["sample_size"],"optional_inputs":["confidence_level_percent","proportion_percent","population_size"],"urls":{"html":"https://tttkmbb.com/statistics/margin-of-error","markdown":"https://tttkmbb.com/statistics/margin-of-error.md","schema":"https://tttkmbb.com/api/v1/calculators/margin-of-error","api":"https://tttkmbb.com/api/v1/calculate/margin-of-error"}},{"calculator_id":"binomial-distribution","entity_type":"calculator","name":"Binomial Distribution Calculator","category":"statistics","tool_name":"calculate_binomial_probability","description":"Computes the probability of exactly, at most, at least, fewer than or more than k successes in n independent trials with success probability p, plus the mean, variance and standard deviation of the distribution.","use_when":"You have a fixed number of independent yes/no trials with a constant success probability (coin flips, defect counts in a batch, conversions among n visitors) and need the probability of a number of successes.","do_not_use_when":"Trials are not independent or p changes, the number of trials is not fixed, or you count events over time or space at an average rate (use poisson-distribution).","required_inputs":["trials","successes","probability_of_success"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/statistics/binomial-distribution","markdown":"https://tttkmbb.com/statistics/binomial-distribution.md","schema":"https://tttkmbb.com/api/v1/calculators/binomial-distribution","api":"https://tttkmbb.com/api/v1/calculate/binomial-distribution"}},{"calculator_id":"poisson-distribution","entity_type":"calculator","name":"Poisson Distribution Calculator","category":"statistics","tool_name":"calculate_poisson_probability","description":"Computes the probability of exactly, at most, at least, fewer than or more than k events when events occur independently at a constant average rate λ per interval, plus the mean, variance and standard deviation.","use_when":"You count independent events over a fixed interval of time or space with a known average rate (calls per hour, defects per metre, arrivals per minute) and need the probability of a given count.","do_not_use_when":"The number of trials is fixed and each has a success probability (use binomial-distribution), the rate varies over the interval, or events cluster (over-dispersion).","required_inputs":["lambda","events"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/statistics/poisson-distribution","markdown":"https://tttkmbb.com/statistics/poisson-distribution.md","schema":"https://tttkmbb.com/api/v1/calculators/poisson-distribution","api":"https://tttkmbb.com/api/v1/calculate/poisson-distribution"}},{"calculator_id":"probability-of-events","entity_type":"calculator","name":"Probability of Two Events Calculator","category":"statistics","tool_name":"calculate_event_probabilities","description":"Combines the probabilities of two events A and B that are either independent or mutually exclusive into the probabilities of both, at least one, exactly one, one but not the other, and neither occurring.","use_when":"You know P(A) and P(B) and how the events relate (independent or mutually exclusive) and need P(A and B), P(A or B), P(neither) or P(exactly one).","do_not_use_when":"The events are dependent with a known conditional probability (apply P(A and B) = P(A)·P(B|A) directly), you need the probability of k successes in repeated trials (use binomial-distribution), or you need an expected payoff (use expected-value).","required_inputs":["probability_a","probability_b"],"optional_inputs":["relationship"],"urls":{"html":"https://tttkmbb.com/statistics/probability-of-events","markdown":"https://tttkmbb.com/statistics/probability-of-events.md","schema":"https://tttkmbb.com/api/v1/calculators/probability-of-events","api":"https://tttkmbb.com/api/v1/calculate/probability-of-events"}},{"calculator_id":"correlation","entity_type":"calculator","name":"Correlation Coefficient 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descriptive-statistics).","required_inputs":["x_values","y_values"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/statistics/correlation","markdown":"https://tttkmbb.com/statistics/correlation.md","schema":"https://tttkmbb.com/api/v1/calculators/correlation","api":"https://tttkmbb.com/api/v1/calculate/correlation"}},{"calculator_id":"linear-regression","entity_type":"calculator","name":"Linear Regression Calculator","category":"statistics","tool_name":"calculate_linear_regression","description":"Fits an ordinary least-squares line to paired (x, y) data and returns the slope, intercept, equation, Pearson r, R², the standard error of the estimate and an optional prediction for a new x.","use_when":"You want the best-fit straight line through paired data, its equation, or a predicted y for a given x (trend lines, calibration curves, simple forecasting).","do_not_use_when":"The relationship is curved or has several predictors (needs polynomial or multiple regression), or you only need the strength of association (use correlation).","required_inputs":["x_values","y_values"],"optional_inputs":["x_new"],"urls":{"html":"https://tttkmbb.com/statistics/linear-regression","markdown":"https://tttkmbb.com/statistics/linear-regression.md","schema":"https://tttkmbb.com/api/v1/calculators/linear-regression","api":"https://tttkmbb.com/api/v1/calculate/linear-regression"}},{"calculator_id":"weighted-average","entity_type":"calculator","name":"Weighted Average Calculator","category":"statistics","tool_name":"calculate_weighted_average","description":"Computes the weighted arithmetic mean Σ(w·x) / Σw of a list of values and a matching list of weights, along with the total weight and the unweighted mean for comparison.","use_when":"Values contribute unequally to an average: course grades with credit weights, portfolio returns by allocation, survey answers with sampling weights, average price over different quantities.","do_not_use_when":"All items count equally (use descriptive-statistics for the plain mean), or the weights are probabilities of outcomes (use expected-value, which also gives the variance).","required_inputs":["values","weights"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/statistics/weighted-average","markdown":"https://tttkmbb.com/statistics/weighted-average.md","schema":"https://tttkmbb.com/api/v1/calculators/weighted-average","api":"https://tttkmbb.com/api/v1/calculate/weighted-average"}},{"calculator_id":"percentile","entity_type":"calculator","name":"Percentile Calculator","category":"statistics","tool_name":"calculate_percentile","description":"For a list of numbers, computes the value at a given percentile (linear interpolation, as in Excel PERCENTILE.INC) and/or the percentile rank of a given value (percentage of values below it, counting ties as half).","use_when":"You need the k-th percentile of a data set (e.g. the 90th percentile response time) or want to know what percentile a particular value falls at within the data.","do_not_use_when":"You want a percentile from a normal distribution rather than actual data (use z-score or normal-distribution), or you need quartiles together with other summary statistics (use descriptive-statistics).","required_inputs":["values"],"optional_inputs":["percentile","value"],"urls":{"html":"https://tttkmbb.com/statistics/percentile","markdown":"https://tttkmbb.com/statistics/percentile.md","schema":"https://tttkmbb.com/api/v1/calculators/percentile","api":"https://tttkmbb.com/api/v1/calculate/percentile"}},{"calculator_id":"expected-value","entity_type":"calculator","name":"Expected Value Calculator","category":"statistics","tool_name":"calculate_expected_value","description":"Computes the expected value E[X] = Σ x·p(x), the variance and the standard deviation of a discrete random variable from its list of outcomes and their probabilities.","use_when":"You have a set of possible outcomes (payoffs, scores, counts) with known probabilities and need the long-run average and its spread: bets, lotteries, insurance, decision analysis.","do_not_use_when":"The probabilities are unknown and you have observed data instead (use descriptive-statistics), or the weights are not probabilities (use weighted-average).","required_inputs":["values","probabilities"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/statistics/expected-value","markdown":"https://tttkmbb.com/statistics/expected-value.md","schema":"https://tttkmbb.com/api/v1/calculators/expected-value","api":"https://tttkmbb.com/api/v1/calculate/expected-value"}},{"calculator_id":"length","entity_type":"calculator","name":"Length Converter","category":"conversion","tool_name":"convert_length","description":"Converts a length or distance between metric (nm to km), imperial/US (in, ft, yd, mi), nautical and astronomical units using exact NIST factors (1 in = 0.0254 m, 1 mi = 1609.344 m).","use_when":"You need a distance, height or length in a different unit, e.g. miles to kilometres, feet to metres or inches to centimetres.","do_not_use_when":"You need an area (use area), a volume (use volume), or a speed (use speed); for walking distance from step counts use steps-to-distance.","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/length","markdown":"https://tttkmbb.com/conversion/length.md","schema":"https://tttkmbb.com/api/v1/calculators/length","api":"https://tttkmbb.com/api/v1/calculate/length"}},{"calculator_id":"mass","entity_type":"calculator","name":"Mass / Weight Converter","category":"conversion","tool_name":"convert_mass","description":"Converts mass between metric units (μg to tonne), avoirdupois units (grain, oz, lb, stone, short and long ton) and carats using the exact definition 1 lb = 0.45359237 kg.","use_when":"You need body weight, ingredient weight or freight mass in another unit, e.g. pounds to kilograms, ounces to grams or stones to pounds.","do_not_use_when":"You need to convert weight to volume (needs a density; use density) or to force in newtons (use force).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/mass","markdown":"https://tttkmbb.com/conversion/mass.md","schema":"https://tttkmbb.com/api/v1/calculators/mass","api":"https://tttkmbb.com/api/v1/calculate/mass"}},{"calculator_id":"temperature","entity_type":"calculator","name":"Temperature Converter","category":"conversion","tool_name":"convert_temperature","description":"Converts temperatures between Celsius, Fahrenheit, Kelvin and Rankine with the exact defining relations (°F = °C × 9/5 + 32, K = °C + 273.15, °R = °F + 459.67) and rejects values below absolute zero.","use_when":"You need a weather, cooking, body or laboratory temperature in another scale, e.g. Fahrenheit to Celsius or Celsius to Kelvin.","do_not_use_when":"You need to convert a temperature difference (a change of 10 °C is 18 °F, not 50 °F: multiply by 9/5 without the offset) or heat energy (use energy).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/temperature","markdown":"https://tttkmbb.com/conversion/temperature.md","schema":"https://tttkmbb.com/api/v1/calculators/temperature","api":"https://tttkmbb.com/api/v1/calculate/temperature"}},{"calculator_id":"area","entity_type":"calculator","name":"Area Converter","category":"conversion","tool_name":"convert_area","description":"Converts areas between metric (mm² to km², hectare) and US/imperial units (in², ft², yd², acre, mi²) using exact factors (1 ft² = 0.09290304 m², 1 acre = 4046.8564224 m²).","use_when":"You need land, floor or surface area in another unit, e.g. square feet to square metres, acres to hectares or square miles to square kilometres.","do_not_use_when":"You need to compute an area from dimensions (use rectangle, circle or triangle-area) or material quantities for a floor (use flooring).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/area","markdown":"https://tttkmbb.com/conversion/area.md","schema":"https://tttkmbb.com/api/v1/calculators/area","api":"https://tttkmbb.com/api/v1/calculate/area"}},{"calculator_id":"volume","entity_type":"calculator","name":"Volume Converter","category":"conversion","tool_name":"convert_volume","description":"Converts volumes between metric units (mL, L, cm³, m³), US customary units (tsp to gallon, in³, ft³, yd³, oil barrel), imperial units (fl oz, pint, quart, gallon) and metric kitchen units, with exact definitions (1 US gal = 3.785411784 L, 1 imperial gal = 4.54609 L).","use_when":"You need a liquid or bulk volume in another unit, e.g. gallons to litres, cubic feet to cubic metres or millilitres to cups.","do_not_use_when":"You need a volume from dimensions (use cylinder, sphere or rectangular-prism), a recipe conversion with tablespoons and cups only (cooking-measurements is a focused subset), or mass from volume (use density).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/volume","markdown":"https://tttkmbb.com/conversion/volume.md","schema":"https://tttkmbb.com/api/v1/calculators/volume","api":"https://tttkmbb.com/api/v1/calculate/volume"}},{"calculator_id":"speed","entity_type":"calculator","name":"Speed Converter","category":"conversion","tool_name":"convert_speed","description":"Converts speeds between m/s, km/h, km/s, mph, ft/s, knots and Mach number using exact factors (1 mph = 0.44704 m/s, 1 kn = 1852/3600 m/s) and 340.294 m/s for Mach 1 at sea level.","use_when":"You need a vehicle, wind, running or aircraft speed in another unit, e.g. km/h to mph, knots to km/h or m/s to ft/s.","do_not_use_when":"You need running pace (min/km or min/mile, use pace-converter) or to derive speed from distance and time (use speed-distance-time).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/speed","markdown":"https://tttkmbb.com/conversion/speed.md","schema":"https://tttkmbb.com/api/v1/calculators/speed","api":"https://tttkmbb.com/api/v1/calculate/speed"}},{"calculator_id":"time","entity_type":"calculator","name":"Time Converter","category":"conversion","tool_name":"convert_time","description":"Converts durations between nanoseconds, microseconds, milliseconds, seconds, minutes, hours, days, weeks, fortnights, 30-day months, 365-day years and Julian years (365.25 days).","use_when":"You need a duration in another unit, e.g. hours to minutes, days to weeks or seconds to milliseconds.","do_not_use_when":"You need the time between two calendar dates (use date-difference), a date shifted by a duration (use add-days), or a clock-time difference (use time-duration).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/time","markdown":"https://tttkmbb.com/conversion/time.md","schema":"https://tttkmbb.com/api/v1/calculators/time","api":"https://tttkmbb.com/api/v1/calculate/time"}},{"calculator_id":"data-storage","entity_type":"calculator","name":"Data Storage Converter","category":"conversion","tool_name":"convert_data_storage","description":"Converts digital storage and transfer sizes between bits, bytes, decimal SI multiples (KB = 1000 B, MB, GB, TB, PB), binary IEC multiples (KiB = 1024 B, MiB, GiB, TiB, PiB) and kilobit/megabit/gigabit/terabit.","use_when":"You need a file, disk or memory size in another unit, e.g. GB to GiB, MB to bits or TB to GB, or want to explain why a '1 TB' drive shows as 931 GiB.","do_not_use_when":"You need transfer time from size and bandwidth (use download-time) or a number in binary/hex (use base-converter).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/data-storage","markdown":"https://tttkmbb.com/conversion/data-storage.md","schema":"https://tttkmbb.com/api/v1/calculators/data-storage","api":"https://tttkmbb.com/api/v1/calculate/data-storage"}},{"calculator_id":"energy","entity_type":"calculator","name":"Energy Converter","category":"conversion","tool_name":"convert_energy","description":"Converts energy between joules (J to GJ), calories (thermochemical cal = 4.184 J, kcal), watt-hours (Wh, kWh, MWh), BTU (International Table, 1055.05585262 J), MMBTU, therm (EC), electronvolts, ergs and foot-pounds.","use_when":"You need an energy amount in another unit, e.g. kWh to MJ, kcal to kJ, BTU to kWh or therms to kWh for utility bills.","do_not_use_when":"You need power (rate of energy, use power), the cost of electricity (use electricity-cost) or calories from macronutrient grams (use calories-from-macros).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/energy","markdown":"https://tttkmbb.com/conversion/energy.md","schema":"https://tttkmbb.com/api/v1/calculators/energy","api":"https://tttkmbb.com/api/v1/calculate/energy"}},{"calculator_id":"pressure","entity_type":"calculator","name":"Pressure Converter","category":"conversion","tool_name":"convert_pressure","description":"Converts pressure between pascals (Pa to MPa), bar/millibar, standard atmospheres, psi and ksi, millimetres and inches of mercury, torr and technical atmospheres (kgf/cm²) using NIST factors (1 psi = 6894.757293168 Pa, 1 atm = 101325 Pa).","use_when":"You need tyre, weather, hydraulic, vacuum or blood pressure in another unit, e.g. psi to bar, atm to kPa or mmHg to kPa.","do_not_use_when":"You need to compute pressure from force and area (a physics calculation, not a unit conversion) or the gas law relation between pressure, volume and temperature (use ideal-gas-law).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/pressure","markdown":"https://tttkmbb.com/conversion/pressure.md","schema":"https://tttkmbb.com/api/v1/calculators/pressure","api":"https://tttkmbb.com/api/v1/calculate/pressure"}},{"calculator_id":"power","entity_type":"calculator","name":"Power Converter","category":"conversion","tool_name":"convert_power","description":"Converts power between watts (W to GW), mechanical horsepower (745.69987158227 W), metric horsepower (735.49875 W), BTU per hour, foot-pounds per second, kcal/h and tons of refrigeration.","use_when":"You need engine, motor, heater or air-conditioner power in another unit, e.g. hp to kW, kW to BTU/h or tons of refrigeration to kW.","do_not_use_when":"You need energy (use energy) or to compute power from work and time or voltage and current (use work-power or electric-power).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/power","markdown":"https://tttkmbb.com/conversion/power.md","schema":"https://tttkmbb.com/api/v1/calculators/power","api":"https://tttkmbb.com/api/v1/calculate/power"}},{"calculator_id":"angle","entity_type":"calculator","name":"Angle Converter","category":"conversion","tool_name":"convert_angle","description":"Converts plane angles between degrees, radians, milliradians, gradians (gon), arcminutes, arcseconds and turns (revolutions) using π rad = 180° = 200 gon = 0.5 turn.","use_when":"You need an angle in another unit, e.g. degrees to radians for trigonometry, arcseconds for astronomy or turns for rotation counts.","do_not_use_when":"You need an angle from a slope or triangle (use slope, right-triangle or triangle-solver) or a rotational speed (use frequency for rpm and rad/s).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/angle","markdown":"https://tttkmbb.com/conversion/angle.md","schema":"https://tttkmbb.com/api/v1/calculators/angle","api":"https://tttkmbb.com/api/v1/calculate/angle"}},{"calculator_id":"fuel-economy","entity_type":"calculator","name":"Fuel Economy Converter","category":"conversion","tool_name":"convert_fuel_economy","description":"Converts fuel consumption between litres per 100 km, kilometres per litre, miles per US gallon and miles per imperial gallon; L/100km is the base and the mpg relations are reciprocal (L/100km = 235.214583 / mpg_US).","use_when":"You need a car's fuel economy in another convention, e.g. mpg to L/100km, L/100km to km/L or US mpg to UK mpg.","do_not_use_when":"You need the fuel cost of a trip (use fuel-cost) or plain volume or distance conversions (use volume, length).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/fuel-economy","markdown":"https://tttkmbb.com/conversion/fuel-economy.md","schema":"https://tttkmbb.com/api/v1/calculators/fuel-economy","api":"https://tttkmbb.com/api/v1/calculate/fuel-economy"}},{"calculator_id":"force","entity_type":"calculator","name":"Force Converter","category":"conversion","tool_name":"convert_force","description":"Converts force between newtons (N, kN), dynes, gram-force, kilogram-force (kilopond), ounce-force, pound-force and kips using exact factors (1 lbf = 4.4482216152605 N, 1 kgf = 9.80665 N).","use_when":"You need a load, thrust or weight-force in another unit, e.g. lbf to N, kgf to N or kN to kips for structural loads.","do_not_use_when":"You need to compute force from mass and acceleration (Newton's second law is a physics calculation, not a unit conversion), a spring force (use hookes-law) or plain mass units (use mass).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/force","markdown":"https://tttkmbb.com/conversion/force.md","schema":"https://tttkmbb.com/api/v1/calculators/force","api":"https://tttkmbb.com/api/v1/calculate/force"}},{"calculator_id":"frequency","entity_type":"calculator","name":"Frequency Converter","category":"conversion","tool_name":"convert_frequency","description":"Converts frequency and rotational speed between hertz (Hz to THz), revolutions per minute, beats per minute, radians per second (angular frequency, ω = 2πf) and degrees per second.","use_when":"You need a rate of rotation or oscillation in another unit, e.g. rpm to Hz, GHz to MHz, rad/s to rpm or bpm to Hz.","do_not_use_when":"You need wavelength from frequency (use wavelength-frequency), a pendulum's period (use pendulum) or a time interval (use time).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/frequency","markdown":"https://tttkmbb.com/conversion/frequency.md","schema":"https://tttkmbb.com/api/v1/calculators/frequency","api":"https://tttkmbb.com/api/v1/calculate/frequency"}},{"calculator_id":"density","entity_type":"calculator","name":"Density Converter","category":"conversion","tool_name":"convert_density","description":"Converts density between kg/m³, g/cm³, g/mL, kg/L, g/L, mg/L, lb/ft³, lb/in³, oz/in³ and lb per US gallon using exact mass and volume definitions (1 lb/ft³ = 16.01846337 kg/m³).","use_when":"You need a material or fluid density in another unit, e.g. g/cm³ to kg/m³, kg/m³ to lb/ft³ or g/mL to lb/gal.","do_not_use_when":"You need to compute density from mass and volume (a physics calculation, not a unit conversion) or concentration in mol/L (use molarity).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/density","markdown":"https://tttkmbb.com/conversion/density.md","schema":"https://tttkmbb.com/api/v1/calculators/density","api":"https://tttkmbb.com/api/v1/calculate/density"}},{"calculator_id":"torque","entity_type":"calculator","name":"Torque Converter","category":"conversion","tool_name":"convert_torque","description":"Converts torque (moment of force) between N·m, kN·m, N·cm, mN·m, lbf·ft, lbf·in, kgf·m, kgf·cm and ozf·in using exact force and length definitions (1 lbf·ft = 1.3558179483 N·m).","use_when":"You need a wrench, bolt or engine torque in another unit, e.g. lb-ft to N·m, N·m to lb-in or kgf·m to N·m.","do_not_use_when":"You need energy in joules or foot-pounds of work (use energy; torque and energy share dimensions but are different quantities) or the force alone (use force).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/torque","markdown":"https://tttkmbb.com/conversion/torque.md","schema":"https://tttkmbb.com/api/v1/calculators/torque","api":"https://tttkmbb.com/api/v1/calculate/torque"}},{"calculator_id":"cooking-measurements","entity_type":"calculator","name":"Cooking Measurement Converter","category":"conversion","tool_name":"convert_cooking_measurements","description":"Converts kitchen volume measures between US customary teaspoons, tablespoons, fluid ounces, cups, pints, quarts and gallons, metric teaspoons (5 mL), tablespoons (15 mL) and cups (250 mL), imperial fluid ounces and pints, and millilitres/litres.","use_when":"You need to convert a recipe quantity between volume measures, e.g. cups to mL, tablespoons to teaspoons or fluid ounces to millilitres.","do_not_use_when":"You need to convert a volume to grams or ounces by weight (that needs the ingredient's density; use cooking-converter), to scale a whole recipe (use recipe-scaler), or non-kitchen volumes such as cubic metres (use volume).","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/conversion/cooking-measurements","markdown":"https://tttkmbb.com/conversion/cooking-measurements.md","schema":"https://tttkmbb.com/api/v1/calculators/cooking-measurements","api":"https://tttkmbb.com/api/v1/calculate/cooking-measurements"}},{"calculator_id":"speed-distance-time","entity_type":"calculator","name":"Speed, Distance & Time Calculator","category":"physics","tool_name":"solve_speed_distance_time","description":"Solves the uniform-motion relation speed = distance / time for whichever of the three quantities is omitted, and reports the speed in m/s, km/h and mph and the time as h:mm:ss.","use_when":"You know any two of distance, elapsed time and average speed for travel at constant (average) speed and need the third.","do_not_use_when":"Speed changes during the motion (use acceleration or free-fall), or you want a running pace per km or mile (use running-pace).","required_inputs":[],"optional_inputs":["distance_m","time_s","speed_m_s"],"urls":{"html":"https://tttkmbb.com/physics/speed-distance-time","markdown":"https://tttkmbb.com/physics/speed-distance-time.md","schema":"https://tttkmbb.com/api/v1/calculators/speed-distance-time","api":"https://tttkmbb.com/api/v1/calculate/speed-distance-time"}},{"calculator_id":"acceleration","entity_type":"calculator","name":"Acceleration Calculator","category":"physics","tool_name":"calculate_acceleration","description":"Computes average acceleration from initial velocity, final velocity and elapsed time, plus the velocity change, the distance covered assuming constant acceleration, and the acceleration expressed in g.","use_when":"You have start and end velocities over a known time interval and need the acceleration or deceleration, or the distance covered while changing speed uniformly (0–100 km/h times, braking).","do_not_use_when":"You know the net force and mass instead of velocities (use force), the motion is vertical under gravity alone (use free-fall), or you only need speed from distance and time (use speed-distance-time).","required_inputs":["final_velocity_m_s","time_s"],"optional_inputs":["initial_velocity_m_s"],"urls":{"html":"https://tttkmbb.com/physics/acceleration","markdown":"https://tttkmbb.com/physics/acceleration.md","schema":"https://tttkmbb.com/api/v1/calculators/acceleration","api":"https://tttkmbb.com/api/v1/calculate/acceleration"}},{"calculator_id":"newtons-second-law","entity_type":"calculator","name":"Force Calculator","category":"physics","tool_name":"calculate_force","description":"Computes net force from mass and acceleration with Newton's second law, reported in newtons, kilonewtons and pounds-force, together with the object's weight under standard gravity.","use_when":"You know a mass and its acceleration (or deceleration) and need the net force, or you need an object's weight in newtons or pounds-force from its mass.","do_not_use_when":"You need the gravitational pull between two bodies (use gravitational-force), a spring force (use hookes-law) or the force in circular motion (use centripetal-force).","required_inputs":["mass_kg","acceleration_m_s2"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/physics/newtons-second-law","markdown":"https://tttkmbb.com/physics/newtons-second-law.md","schema":"https://tttkmbb.com/api/v1/calculators/newtons-second-law","api":"https://tttkmbb.com/api/v1/calculate/newtons-second-law"}},{"calculator_id":"kinetic-energy","entity_type":"calculator","name":"Kinetic Energy Calculator","category":"physics","tool_name":"calculate_kinetic_energy","description":"Computes the translational kinetic energy of a moving mass from KE = ½·m·v², reported in joules, kilojoules, kilowatt-hours and kilocalories.","use_when":"You need the energy of motion of an object of known mass and speed (vehicle, projectile, ball), for example to compare impact or braking energies.","do_not_use_when":"Rotation contributes significantly (rotational energy ½·I·ω² is not included), speeds approach the speed of light (relativistic formula needed), or you need energy from height (use potential-energy).","required_inputs":["mass_kg","velocity_m_s"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/physics/kinetic-energy","markdown":"https://tttkmbb.com/physics/kinetic-energy.md","schema":"https://tttkmbb.com/api/v1/calculators/kinetic-energy","api":"https://tttkmbb.com/api/v1/calculate/kinetic-energy"}},{"calculator_id":"potential-energy","entity_type":"calculator","name":"Potential Energy Calculator","category":"physics","tool_name":"calculate_potential_energy","description":"Computes the gravitational potential energy of a mass raised to a height near a planet's surface with PE = m·g·h (standard gravity by default), and the speed the mass would reach if it fell that height freely.","use_when":"You need the energy stored by lifting a mass to a height, the minimum work to lift it, or the energy released when it falls (lifted loads, pumped hydro, dropped objects).","do_not_use_when":"Heights are a significant fraction of the planet's radius (g is not constant; use gravitational-force), or you need elastic energy (use hookes-law) or energy of motion (use kinetic-energy).","required_inputs":["mass_kg","height_m"],"optional_inputs":["gravity_m_s2"],"urls":{"html":"https://tttkmbb.com/physics/potential-energy","markdown":"https://tttkmbb.com/physics/potential-energy.md","schema":"https://tttkmbb.com/api/v1/calculators/potential-energy","api":"https://tttkmbb.com/api/v1/calculate/potential-energy"}},{"calculator_id":"work-power","entity_type":"calculator","name":"Work & Power Calculator","category":"physics","tool_name":"calculate_work_and_power","description":"Computes the mechanical work done by a constant force over a displacement, allowing for the angle between force and motion, and the average power when the duration is supplied.","use_when":"You know a constant force, the distance it acts over (optionally the angle and the time taken) and need the work in joules or the average power in watts, kilowatts or horsepower.","do_not_use_when":"The force varies with position (for springs use hookes-law), you need electrical power from volts and amps (use electric-power), or you need energy of motion (use kinetic-energy).","required_inputs":["force_n","distance_m"],"optional_inputs":["angle_degrees","time_s"],"urls":{"html":"https://tttkmbb.com/physics/work-power","markdown":"https://tttkmbb.com/physics/work-power.md","schema":"https://tttkmbb.com/api/v1/calculators/work-power","api":"https://tttkmbb.com/api/v1/calculate/work-power"}},{"calculator_id":"momentum","entity_type":"calculator","name":"Momentum Calculator","category":"physics","tool_name":"calculate_momentum","description":"Computes linear momentum from mass and velocity, the matching kinetic energy, and, when a stopping time is given, the average force needed to bring the object to rest (impulse–momentum theorem).","use_when":"You need an object's momentum, or the average force involved in stopping or launching it over a known time (collisions, braking, catching a ball).","do_not_use_when":"You need the outcome of a two-body collision (conservation of momentum between two objects is not implemented), or only the energy of motion (use kinetic-energy).","required_inputs":["mass_kg","velocity_m_s"],"optional_inputs":["stop_time_s"],"urls":{"html":"https://tttkmbb.com/physics/momentum","markdown":"https://tttkmbb.com/physics/momentum.md","schema":"https://tttkmbb.com/api/v1/calculators/momentum","api":"https://tttkmbb.com/api/v1/calculate/momentum"}},{"calculator_id":"free-fall","entity_type":"calculator","name":"Free Fall Calculator","category":"physics","tool_name":"calculate_free_fall","description":"Computes the time to fall a given height from rest, or the height fallen in a given time, together with the final (impact) velocity, using h = ½·g·t² with no air resistance.","use_when":"An object is dropped from rest near a planet's surface and you need how long it falls, how far, or how fast it lands (a dropped tool, a stone in a well).","do_not_use_when":"Air drag matters (light or fast objects, skydivers, long falls near terminal velocity), the object has an initial velocity or launch angle (use projectile-motion), or heights are comparable to the planet's radius.","required_inputs":[],"optional_inputs":["height_m","time_s","gravity_m_s2"],"urls":{"html":"https://tttkmbb.com/physics/free-fall","markdown":"https://tttkmbb.com/physics/free-fall.md","schema":"https://tttkmbb.com/api/v1/calculators/free-fall","api":"https://tttkmbb.com/api/v1/calculate/free-fall"}},{"calculator_id":"projectile-motion","entity_type":"calculator","name":"Projectile Motion 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free-fall).","required_inputs":["initial_speed_m_s","angle_degrees"],"optional_inputs":["initial_height_m","gravity_m_s2"],"urls":{"html":"https://tttkmbb.com/physics/projectile-motion","markdown":"https://tttkmbb.com/physics/projectile-motion.md","schema":"https://tttkmbb.com/api/v1/calculators/projectile-motion","api":"https://tttkmbb.com/api/v1/calculate/projectile-motion"}},{"calculator_id":"ohms-law","entity_type":"calculator","name":"Ohm's Law Calculator","category":"physics","tool_name":"solve_ohms_law","description":"Solves Ohm's law V = I·R for whichever of voltage, current or resistance is omitted and reports the electrical power dissipated (P = V·I).","use_when":"You know two of voltage, current and resistance in a DC or purely resistive circuit and need the third and the power.","do_not_use_when":"The load is reactive (inductors or capacitors require impedance, not resistance), you want energy cost over time (use electric-power), or you need the equivalent resistance of several resistors (use resistors-series-parallel).","required_inputs":[],"optional_inputs":["voltage_v","current_a","resistance_ohm"],"urls":{"html":"https://tttkmbb.com/physics/ohms-law","markdown":"https://tttkmbb.com/physics/ohms-law.md","schema":"https://tttkmbb.com/api/v1/calculators/ohms-law","api":"https://tttkmbb.com/api/v1/calculate/ohms-law"}},{"calculator_id":"electric-power","entity_type":"calculator","name":"Electric Power Calculator","category":"physics","tool_name":"calculate_electric_power","description":"Computes electrical power from voltage and current (or the current drawn by a known power at a given voltage), the equivalent resistance, and, with hours of use and a tariff, the energy in kWh and its cost.","use_when":"You need the wattage or amperage of an appliance, whether it fits a circuit rating, or how much energy and money it uses over a period.","do_not_use_when":"The load has a power factor below 1 (motors, some electronics: P = V·I·cos φ), you only need V, I and R relations (use ohms-law), or you want a multi-appliance bill (use electricity-cost).","required_inputs":["voltage_v"],"optional_inputs":["current_a","power_w","usage_hours","price_per_kwh"],"urls":{"html":"https://tttkmbb.com/physics/electric-power","markdown":"https://tttkmbb.com/physics/electric-power.md","schema":"https://tttkmbb.com/api/v1/calculators/electric-power","api":"https://tttkmbb.com/api/v1/calculate/electric-power"}},{"calculator_id":"density-mass-volume","entity_type":"calculator","name":"Density Calculator","category":"physics","tool_name":"solve_density","description":"Solves ρ = m / V for whichever of density, mass or volume is omitted, and reports density in kg/m³ and g/cm³, volume in litres and cm³, and the specific gravity relative to water.","use_when":"You know two of mass, volume and density of an object or substance and need the third, e.g. the mass of a steel block, the volume of a litre of oil, or whether an object floats.","do_not_use_when":"The substance is a gas whose density depends strongly on pressure and temperature (use ideal-gas-law), or you need the volume of a shape first (use sphere, cylinder or rectangular-prism).","required_inputs":[],"optional_inputs":["mass_kg","volume_m3","density_kg_m3"],"urls":{"html":"https://tttkmbb.com/physics/density-mass-volume","markdown":"https://tttkmbb.com/physics/density-mass-volume.md","schema":"https://tttkmbb.com/api/v1/calculators/density-mass-volume","api":"https://tttkmbb.com/api/v1/calculate/density-mass-volume"}},{"calculator_id":"pressure-force-area","entity_type":"calculator","name":"Pressure Calculator","category":"physics","tool_name":"calculate_pressure","description":"Computes pressure as force divided by the area it acts on, and reports it in pascals, kilopascals, bar, pounds per square inch and standard atmospheres.","use_when":"You know a force (or a weight in newtons) and the contact area and need the pressure: a load on a footing, a hydraulic piston, a heel on a floor.","do_not_use_when":"You need fluid pressure at depth (P = ρ·g·h is not implemented), gas pressure from temperature and amount (use ideal-gas-law), or the force from a mass first (use force).","required_inputs":["force_n","area_m2"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/physics/pressure-force-area","markdown":"https://tttkmbb.com/physics/pressure-force-area.md","schema":"https://tttkmbb.com/api/v1/calculators/pressure-force-area","api":"https://tttkmbb.com/api/v1/calculate/pressure-force-area"}},{"calculator_id":"wavelength-frequency","entity_type":"calculator","name":"Wavelength & Frequency Calculator","category":"physics","tool_name":"convert_wavelength_frequency","description":"Converts between wavelength and frequency for a wave of known propagation speed (default: the speed of light in vacuum) and, for electromagnetic waves in vacuum, reports the photon energy E = h·f in joules and electronvolts.","use_when":"You know either the wavelength or the frequency of a light, radio or sound wave and need the other, or you need the photon energy of light of a given wavelength.","do_not_use_when":"The wave travels in a dispersive medium (glass, water) unless you supply the correct phase speed, or you need Doppler shifts or refraction.","required_inputs":[],"optional_inputs":["wavelength_m","frequency_hz","wave_speed_m_s"],"urls":{"html":"https://tttkmbb.com/physics/wavelength-frequency","markdown":"https://tttkmbb.com/physics/wavelength-frequency.md","schema":"https://tttkmbb.com/api/v1/calculators/wavelength-frequency","api":"https://tttkmbb.com/api/v1/calculate/wavelength-frequency"}},{"calculator_id":"pendulum","entity_type":"calculator","name":"Pendulum Period Calculator","category":"physics","tool_name":"calculate_pendulum_period","description":"Computes the period, frequency and angular frequency of a simple pendulum from its length with the small-angle formula T = 2π√(L/g); when an amplitude is given it also returns the exact period from the arithmetic–geometric mean.","use_when":"You need how long a pendulum of known length takes to swing on Earth or another body, or how much a large swing angle lengthens the period.","do_not_use_when":"The bob's size or the rod's mass is not negligible (physical pendulum, T = 2π√(I / (m·g·d))), or the oscillator is a mass on a spring (use hookes-law).","required_inputs":["length_m"],"optional_inputs":["gravity_m_s2","amplitude_degrees"],"urls":{"html":"https://tttkmbb.com/physics/pendulum","markdown":"https://tttkmbb.com/physics/pendulum.md","schema":"https://tttkmbb.com/api/v1/calculators/pendulum","api":"https://tttkmbb.com/api/v1/calculate/pendulum"}},{"calculator_id":"hookes-law","entity_type":"calculator","name":"Hooke's Law Calculator","category":"physics","tool_name":"calculate_hookes_law","description":"Computes the restoring force of a linear spring and the elastic potential energy stored at a given displacement, plus the natural period and frequency of a mass on that spring when a mass is supplied.","use_when":"You know a spring constant and how far the spring is stretched or compressed and need the force or stored energy, or the oscillation period of a spring–mass system.","do_not_use_when":"The spring is loaded beyond its elastic (linear) limit, or you need gravitational energy (use potential-energy) or a pendulum's period (use pendulum).","required_inputs":["spring_constant_n_m","displacement_m"],"optional_inputs":["mass_kg"],"urls":{"html":"https://tttkmbb.com/physics/hookes-law","markdown":"https://tttkmbb.com/physics/hookes-law.md","schema":"https://tttkmbb.com/api/v1/calculators/hookes-law","api":"https://tttkmbb.com/api/v1/calculate/hookes-law"}},{"calculator_id":"gravitational-force","entity_type":"calculator","name":"Gravitational Force Calculator","category":"physics","tool_name":"calculate_gravitational_force","description":"Computes the attractive gravitational force between two point or spherically symmetric masses at a given centre-to-centre distance with Newton's law and the CODATA 2018 value of G, plus the acceleration each mass experiences.","use_when":"You need the gravitational pull between two bodies (planet and satellite, star and planet, two laboratory masses) or the surface gravity of a body from its mass and radius.","do_not_use_when":"You only need weight near Earth's surface (use force with 9.80665 m/s²), or relativistic effects matter (near black holes, precision orbits).","required_inputs":["mass1_kg","mass2_kg","distance_m"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/physics/gravitational-force","markdown":"https://tttkmbb.com/physics/gravitational-force.md","schema":"https://tttkmbb.com/api/v1/calculators/gravitational-force","api":"https://tttkmbb.com/api/v1/calculate/gravitational-force"}},{"calculator_id":"centripetal-force","entity_type":"calculator","name":"Centripetal Force Calculator","category":"physics","tool_name":"calculate_centripetal_force","description":"Computes the centripetal (centre-seeking) force and acceleration needed to keep a mass moving in a circle of given radius at a given speed, plus the angular velocity, rotation period and rpm.","use_when":"You need the force on a car in a bend, a mass on a string, a satellite or a centrifuge sample from mass, tangential speed and radius, or the g-load of circular motion.","do_not_use_when":"You know the angular speed (rpm) rather than the tangential speed (compute v = ω·r first), or the motion is not circular at constant speed.","required_inputs":["mass_kg","velocity_m_s","radius_m"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/physics/centripetal-force","markdown":"https://tttkmbb.com/physics/centripetal-force.md","schema":"https://tttkmbb.com/api/v1/calculators/centripetal-force","api":"https://tttkmbb.com/api/v1/calculate/centripetal-force"}},{"calculator_id":"specific-heat","entity_type":"calculator","name":"Specific Heat Calculator","category":"physics","tool_name":"calculate_specific_heat_energy","description":"Computes the heat energy needed to change the temperature of a mass of material by a given amount from Q = m·c·ΔT, using the specific heat capacity of liquid water (4186 J/(kg·K)) by default.","use_when":"You need how much energy heats or cools a known mass of water, metal or another substance by a given number of degrees, without a phase change.","do_not_use_when":"The substance melts, boils or freezes within the range (latent heat is not included), or you need the final temperature when two bodies are mixed (calorimetry is not implemented).","required_inputs":["mass_kg","temperature_change_k"],"optional_inputs":["specific_heat_j_kg_k"],"urls":{"html":"https://tttkmbb.com/physics/specific-heat","markdown":"https://tttkmbb.com/physics/specific-heat.md","schema":"https://tttkmbb.com/api/v1/calculators/specific-heat","api":"https://tttkmbb.com/api/v1/calculate/specific-heat"}},{"calculator_id":"resistors-series-parallel","entity_type":"calculator","name":"Resistors in Series and Parallel Calculator","category":"physics","tool_name":"calculate_resistors_series_parallel","description":"Computes the equivalent resistance of a list of resistors connected all in series (sum) and all in parallel (reciprocal of the sum of reciprocals), plus the parallel conductance.","use_when":"You have two or more resistor values and need the total resistance if they are wired in series or in parallel, or want to check a parallel combination against a target value.","do_not_use_when":"The network mixes series and parallel branches (reduce it group by group with repeated calls), the components are capacitors or inductors, or you need voltage, current or power for one resistor (use ohms-law).","required_inputs":["resistances_ohm"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/physics/resistors-series-parallel","markdown":"https://tttkmbb.com/physics/resistors-series-parallel.md","schema":"https://tttkmbb.com/api/v1/calculators/resistors-series-parallel","api":"https://tttkmbb.com/api/v1/calculate/resistors-series-parallel"}},{"calculator_id":"molar-mass","entity_type":"calculator","name":"Molar Mass Calculator","category":"chemistry","tool_name":"calculate_molar_mass","description":"Parses a chemical formula (including brackets, nested groups and hydrates) and sums IUPAC 2021 standard atomic weights to give the molar mass in g/mol, plus the atom count and mass-percent composition of each element.","use_when":"You have a chemical formula and need its molar mass (molecular weight), the number of atoms of each element, or its elemental mass-percent composition.","do_not_use_when":"You already know the molar mass and want to convert between grams and moles (use moles-mass) or need a solution concentration (use molarity).","required_inputs":["formula"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/chemistry/molar-mass","markdown":"https://tttkmbb.com/chemistry/molar-mass.md","schema":"https://tttkmbb.com/api/v1/calculators/molar-mass","api":"https://tttkmbb.com/api/v1/calculate/molar-mass"}},{"calculator_id":"moles-mass","entity_type":"calculator","name":"Moles to Grams Calculator","category":"chemistry","tool_name":"convert_moles_and_mass","description":"Converts between mass in grams and amount in moles using the molar mass (from a formula or given directly), and reports the number of molecules or formula units from the Avogadro constant. Any two of molar mass, mass and moles give the third.","use_when":"You need to convert grams to moles or moles to grams for a substance, count the molecules in a sample, or back out a molar mass from a measured mass and amount.","do_not_use_when":"You only need the molar mass of a formula (use molar-mass), or you want a concentration in mol/L (use molarity).","required_inputs":[],"optional_inputs":["formula","molar_mass_g_mol","mass_g","moles"],"urls":{"html":"https://tttkmbb.com/chemistry/moles-mass","markdown":"https://tttkmbb.com/chemistry/moles-mass.md","schema":"https://tttkmbb.com/api/v1/calculators/moles-mass","api":"https://tttkmbb.com/api/v1/calculate/moles-mass"}},{"calculator_id":"molarity","entity_type":"calculator","name":"Molarity Calculator","category":"chemistry","tool_name":"calculate_molarity","description":"Computes molar concentration (mol/L) of a solution from the amount of solute (moles, or mass with a formula or molar mass) and the solution volume, or the moles and mass of solute needed to prepare a target molarity.","use_when":"You need the molarity of a solution from what was dissolved, or the grams of solute required for a given volume and target concentration.","do_not_use_when":"You are diluting an existing stock solution (use dilution), or you need a mass-based concentration such as % w/w, ppm or ppb (use mass-percent).","required_inputs":["volume_l"],"optional_inputs":["moles","mass_g","formula","molar_mass_g_mol","target_molarity_mol_per_l"],"urls":{"html":"https://tttkmbb.com/chemistry/molarity","markdown":"https://tttkmbb.com/chemistry/molarity.md","schema":"https://tttkmbb.com/api/v1/calculators/molarity","api":"https://tttkmbb.com/api/v1/calculate/molarity"}},{"calculator_id":"dilution","entity_type":"calculator","name":"Dilution Calculator","category":"chemistry","tool_name":"calculate_dilution","description":"Applies the dilution equation C1·V1 = C2·V2 to find the missing one of stock concentration, stock volume, final concentration or final volume, plus the solvent to add and the dilution factor.","use_when":"You are diluting a stock solution and need how much stock to take, the final volume to make up, or the concentration that results.","do_not_use_when":"You are preparing a solution from solid solute (use molarity) or the concentrations are in mass percent with very different densities (C1V1 = C2V2 assumes volumes are additive and the unit is amount per volume).","required_inputs":[],"optional_inputs":["stock_concentration","stock_volume","final_concentration","final_volume"],"urls":{"html":"https://tttkmbb.com/chemistry/dilution","markdown":"https://tttkmbb.com/chemistry/dilution.md","schema":"https://tttkmbb.com/api/v1/calculators/dilution","api":"https://tttkmbb.com/api/v1/calculate/dilution"}},{"calculator_id":"ideal-gas-law","entity_type":"calculator","name":"Ideal Gas Law Calculator","category":"chemistry","tool_name":"solve_ideal_gas_law","description":"Solves the ideal gas equation PV = nRT for whichever of pressure, volume, amount or temperature is left empty, with pressure in atm, kPa, bar, mmHg or psi and temperature in °C, K or °F.","use_when":"You know three of pressure, volume, moles and temperature of a gas and need the fourth, or the molar volume at given conditions.","do_not_use_when":"The gas is near condensation or at very high pressure (use a real-gas equation such as van der Waals), or you need the mass of gas without knowing its molar mass (combine with moles-mass).","required_inputs":[],"optional_inputs":["pressure","pressure_unit","volume_l","moles","temperature","temperature_unit"],"urls":{"html":"https://tttkmbb.com/chemistry/ideal-gas-law","markdown":"https://tttkmbb.com/chemistry/ideal-gas-law.md","schema":"https://tttkmbb.com/api/v1/calculators/ideal-gas-law","api":"https://tttkmbb.com/api/v1/calculate/ideal-gas-law"}},{"calculator_id":"ph","entity_type":"calculator","name":"pH Calculator","category":"chemistry","tool_name":"calculate_ph","description":"Converts between pH, pOH, hydrogen-ion concentration and hydroxide-ion concentration at 25 °C (Kw = 1.0×10⁻¹⁴) from any one of them, and classifies the solution as acidic, neutral or basic.","use_when":"You know one of pH, pOH, [H⁺] or [OH⁻] for an aqueous solution (for example the concentration of a fully dissociated strong acid or base) and need the others.","do_not_use_when":"The solution contains a weak acid or base or a buffer, where [H⁺] is not equal to the nominal concentration (use henderson-hasselbalch for buffers), or the temperature differs a lot from 25 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departure.","do_not_use_when":"You need the number of days between two known dates (use date-difference) or want to skip weekends when counting (not supported here).","required_inputs":["days"],"optional_inputs":["start_date"],"urls":{"html":"https://tttkmbb.com/everyday/add-days","markdown":"https://tttkmbb.com/everyday/add-days.md","schema":"https://tttkmbb.com/api/v1/calculators/add-days","api":"https://tttkmbb.com/api/v1/calculate/add-days"}},{"calculator_id":"days-until","entity_type":"calculator","name":"Days Until Calculator","category":"everyday","tool_name":"calculate_days_until","description":"Counts the days from a reference date (default today) to a target date and reports the countdown as weeks and days, approximate months, a calendar breakdown and the target's weekday.","use_when":"You need a countdown to an event, deadline or holiday, or how many days ago a date was.","do_not_use_when":"You need business days or an inclusive count between two dates (use date-difference), 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(use fuel-cost).","required_inputs":["total_bill","people"],"optional_inputs":["tip_percent"],"urls":{"html":"https://tttkmbb.com/everyday/bill-split","markdown":"https://tttkmbb.com/everyday/bill-split.md","schema":"https://tttkmbb.com/api/v1/calculators/bill-split","api":"https://tttkmbb.com/api/v1/calculate/bill-split"}},{"calculator_id":"unit-price","entity_type":"calculator","name":"Unit Price Comparison Calculator","category":"everyday","tool_name":"calculate_unit_price","description":"Divides each price by its quantity to get the price per unit, tells which of two options is cheaper per unit and by what percentage.","use_when":"You are comparing two package sizes or brands of the same product (e.g. 500 g for 3.49 vs 1 kg for 5.99) and want the better value per unit.","do_not_use_when":"The two quantities are in different units (convert them to the same unit first, e.g. with mass or volume), or you need a discount on a single price (use 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rates (adjust words_per_minute).","required_inputs":["word_count"],"optional_inputs":["words_per_minute"],"urls":{"html":"https://tttkmbb.com/everyday/reading-time","markdown":"https://tttkmbb.com/everyday/reading-time.md","schema":"https://tttkmbb.com/api/v1/calculators/reading-time","api":"https://tttkmbb.com/api/v1/calculate/reading-time"}},{"calculator_id":"typing-speed","entity_type":"calculator","name":"Typing Speed Calculator","category":"everyday","tool_name":"calculate_typing_speed","description":"Computes gross words per minute from characters typed (one word = 5 characters) or from a word count, then net WPM after penalising uncorrected errors, plus accuracy and characters per minute.","use_when":"You timed a typing test and know the characters or words typed, the time and the number of errors, and want standard WPM figures.","do_not_use_when":"You need reading speed (use reading-time) or the test software already reports WPM under its own error 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weighted-average).","required_inputs":["grade_points"],"optional_inputs":["credits"],"urls":{"html":"https://tttkmbb.com/everyday/gpa","markdown":"https://tttkmbb.com/everyday/gpa.md","schema":"https://tttkmbb.com/api/v1/calculators/gpa","api":"https://tttkmbb.com/api/v1/calculate/gpa"}},{"calculator_id":"final-grade","entity_type":"calculator","name":"Final Grade Calculator","category":"everyday","tool_name":"calculate_required_final_grade","description":"Solves the weighted-average grade equation for the final exam score required to reach a desired overall grade, given the current grade and the final's weight, and reports whether that score is achievable.","use_when":"You know your current course grade and the final exam's weight and want the minimum final score for a target grade.","do_not_use_when":"Grades are combined by points or categories rather than a percentage weight (compute the weighted mean directly with weighted-average), or you need a GPA (use gpa).","required_inputs":["current_grade_percent","final_weight_percent","desired_grade_percent"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/everyday/final-grade","markdown":"https://tttkmbb.com/everyday/final-grade.md","schema":"https://tttkmbb.com/api/v1/calculators/final-grade","api":"https://tttkmbb.com/api/v1/calculate/final-grade"}},{"calculator_id":"sleep-cycles","entity_type":"calculator","name":"Sleep Cycle Calculator","category":"everyday","tool_name":"calculate_sleep_cycle_times","description":"Suggests bedtimes for a given wake-up time, or wake-up times for a given bedtime, so that sleep ends at the boundary of a full sleep cycle (default 90 minutes) after a typical time to fall asleep (default 14 minutes).","use_when":"You want to pick a bedtime or alarm time that completes 3–6 whole sleep cycles instead of waking mid-cycle.","do_not_use_when":"You have a sleep disorder or shift-work schedule needing clinical advice; cycle length varies between people and through the night, so treat the times as approximations.","required_inputs":["mode","time"],"optional_inputs":["fall_asleep_minutes","cycle_minutes"],"urls":{"html":"https://tttkmbb.com/everyday/sleep-cycles","markdown":"https://tttkmbb.com/everyday/sleep-cycles.md","schema":"https://tttkmbb.com/api/v1/calculators/sleep-cycles","api":"https://tttkmbb.com/api/v1/calculate/sleep-cycles"}},{"calculator_id":"aspect-ratio","entity_type":"calculator","name":"Aspect Ratio Calculator","category":"everyday","tool_name":"calculate_aspect_ratio","description":"Reduces a width and height to their simplest ratio and decimal value, identifies the closest common ratio (16:9, 4:3, 3:2, 21:9 …) and scales the dimensions to a new width or height while keeping the ratio.","use_when":"You need the aspect ratio of an image, screen or video, or the matching height for a new width (or width for a new height) when resizing.","do_not_use_when":"You need pixel density, file size or a crop to a different ratio; 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date-difference).","required_inputs":["year"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/everyday/leap-year","markdown":"https://tttkmbb.com/everyday/leap-year.md","schema":"https://tttkmbb.com/api/v1/calculators/leap-year","api":"https://tttkmbb.com/api/v1/calculate/leap-year"}},{"calculator_id":"roman-numeral","entity_type":"calculator","name":"Roman Numeral Converter","category":"everyday","tool_name":"convert_roman_numeral","description":"Converts an integer from 1 to 3999 into standard (subtractive-notation) Roman numerals, or parses a Roman numeral back into a number, and shows the value of each symbol group.","use_when":"You need to write a year, chapter or clock number in Roman numerals, or read one such as MCMXCIV.","do_not_use_when":"The number is 0, negative, 4000 or larger, or not an integer (standard Roman numerals cannot express these); for other number systems use 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salary-converter).","required_inputs":["start_time","end_time"],"optional_inputs":["break_minutes","days_per_week","hourly_rate"],"urls":{"html":"https://tttkmbb.com/everyday/work-hours","markdown":"https://tttkmbb.com/everyday/work-hours.md","schema":"https://tttkmbb.com/api/v1/calculators/work-hours","api":"https://tttkmbb.com/api/v1/calculate/work-hours"}},{"calculator_id":"recipe-scaler","entity_type":"calculator","name":"Recipe Scaler","category":"food","tool_name":"scale_recipe","description":"Computes the conversion factor between an original and a desired number of servings and multiplies a list of ingredient amounts by it.","use_when":"You need to enlarge or reduce a recipe for a different number of servings and want every ingredient quantity scaled consistently.","do_not_use_when":"You need to convert between measurement units (use cooking-converter) or to work with baker's percentages for dough (use bakers-percentage).","required_inputs":["original_servings","desired_servings"],"optional_inputs":["ingredient_amounts"],"urls":{"html":"https://tttkmbb.com/food/recipe-scaler","markdown":"https://tttkmbb.com/food/recipe-scaler.md","schema":"https://tttkmbb.com/api/v1/calculators/recipe-scaler","api":"https://tttkmbb.com/api/v1/calculate/recipe-scaler"}},{"calculator_id":"cooking-converter","entity_type":"calculator","name":"Cooking Measurement Converter","category":"food","tool_name":"convert_cooking_measurement","description":"Converts a kitchen volume between US customary units (teaspoon, tablespoon, fluid ounce, cup, pint, quart), the 250 ml metric cup, millilitres and litres using the exact US definitions.","use_when":"A recipe uses cups, tablespoons or fluid ounces and you need millilitres (or the reverse), or you need to switch between US and metric cups.","do_not_use_when":"You need grams: converting volume to weight requires the ingredient's density (e.g. 1 US cup of flour ≈ 120 g but of water ≈ 237 g), which this calculator does not do.","required_inputs":["value","from_unit","to_unit"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/food/cooking-converter","markdown":"https://tttkmbb.com/food/cooking-converter.md","schema":"https://tttkmbb.com/api/v1/calculators/cooking-converter","api":"https://tttkmbb.com/api/v1/calculate/cooking-converter"}},{"calculator_id":"coffee-ratio","entity_type":"calculator","name":"Coffee Ratio Calculator","category":"food","tool_name":"calculate_coffee_ratio","description":"Computes the grams of ground coffee for a given amount of water (or the water for a given dose) from a brew ratio, using method-specific default ratios (drip and pour-over 1:16, French press 1:15, AeroPress 1:13, cold brew concentrate 1:8, espresso 1:2) or a custom ratio.","use_when":"You want to know how much coffee to use for a certain volume of water, how much water a dose of coffee needs, or the ratio implied by amounts you already used.","do_not_use_when":"You need caffeine content or extraction/TDS calculations; ratios here are by weight of dry coffee and water only.","required_inputs":[],"optional_inputs":["water_ml","coffee_g","brew_method","ratio"],"urls":{"html":"https://tttkmbb.com/food/coffee-ratio","markdown":"https://tttkmbb.com/food/coffee-ratio.md","schema":"https://tttkmbb.com/api/v1/calculators/coffee-ratio","api":"https://tttkmbb.com/api/v1/calculate/coffee-ratio"}},{"calculator_id":"calories-from-macros","entity_type":"calculator","name":"Calories from Macros Calculator","category":"food","tool_name":"calculate_calories_from_macros","description":"Converts grams of protein, carbohydrate, fat and alcohol into kilocalories and kilojoules with the Atwater general factors (4 / 4 / 9 / 7 kcal per gram) and reports each macronutrient's share of total energy.","use_when":"You have the macronutrient grams of a food, meal or daily intake and need total calories or the percentage split, e.g. to check a food label or diet plan.","do_not_use_when":"You want to go the other way, from a calorie target to gram targets (use macros), or need calorie needs (use tdee).","required_inputs":["protein_g","carbs_g","fat_g"],"optional_inputs":["alcohol_g","fiber_g"],"urls":{"html":"https://tttkmbb.com/food/calories-from-macros","markdown":"https://tttkmbb.com/food/calories-from-macros.md","schema":"https://tttkmbb.com/api/v1/calculators/calories-from-macros","api":"https://tttkmbb.com/api/v1/calculate/calories-from-macros"}},{"calculator_id":"pizza-dough","entity_type":"calculator","name":"Pizza Dough Calculator","category":"food","tool_name":"calculate_pizza_dough","description":"Computes the flour, water, salt, yeast and oil in grams for a number of pizza dough balls of a given weight from baker's percentages (hydration, salt, yeast, oil as % of flour).","use_when":"You want exact gram amounts for a batch of pizza dough balls, e.g. 4 balls of 250 g at 62 % hydration.","do_not_use_when":"You are starting from a known flour weight or need custom ingredients (use bakers-percentage), or you need bread with preferments or several flours.","required_inputs":["number_of_pizzas"],"optional_inputs":["ball_weight_g","hydration_percent","salt_percent","yeast_percent","oil_percent"],"urls":{"html":"https://tttkmbb.com/food/pizza-dough","markdown":"https://tttkmbb.com/food/pizza-dough.md","schema":"https://tttkmbb.com/api/v1/calculators/pizza-dough","api":"https://tttkmbb.com/api/v1/calculate/pizza-dough"}},{"calculator_id":"brine","entity_type":"calculator","name":"Brine Calculator","category":"food","tool_name":"calculate_brine","description":"Computes the grams of salt (and optional sugar) for a wet brine from the water volume and a percentage concentration expressed relative to the water weight (6 % = 60 g per litre).","use_when":"You are brining poultry, pork or vegetables and need the salt for a given amount of water at a target strength.","do_not_use_when":"You need a dry brine or an equilibrium brine based on the meat's weight (salt = 0.5–2 % of meat + water weight), or curing with nitrite salts, which follow different rules.","required_inputs":["water_liters"],"optional_inputs":["salt_percent","sugar_percent"],"urls":{"html":"https://tttkmbb.com/food/brine","markdown":"https://tttkmbb.com/food/brine.md","schema":"https://tttkmbb.com/api/v1/calculators/brine","api":"https://tttkmbb.com/api/v1/calculate/brine"}},{"calculator_id":"rice-water","entity_type":"calculator","name":"Rice to Water Ratio Calculator","category":"food","tool_name":"calculate_rice_water_ratio","description":"Computes the water needed for a quantity of uncooked rice (cups or grams) using absorption-method ratios by rice type: long-grain white 1:1.5, jasmine 1:1.25, basmati 1:1.5, brown 1:2, sushi 1:1.1, wild 1:3.","use_when":"You are cooking rice by the absorption method (tight lid or rice cooker) and need the water amount for a given quantity and type of rice.","do_not_use_when":"You boil rice in excess water and drain it (ratio irrelevant), cook risotto or paella, or follow a package instruction that specifies a different ratio for that product.","required_inputs":[],"optional_inputs":["rice_cups","rice_g","rice_type"],"urls":{"html":"https://tttkmbb.com/food/rice-water","markdown":"https://tttkmbb.com/food/rice-water.md","schema":"https://tttkmbb.com/api/v1/calculators/rice-water","api":"https://tttkmbb.com/api/v1/calculate/rice-water"}},{"calculator_id":"bakers-percentage","entity_type":"calculator","name":"Baker's Percentage Calculator","category":"food","tool_name":"calculate_bakers_percentage","description":"Converts a bread or dough formula between baker's percentages and grams: flour is 100 %, every other ingredient is expressed relative to flour weight; works in both directions and reports total dough weight and hydration.","use_when":"You know the flour weight and the formula percentages (or the ingredient grams) and want the other representation, e.g. to scale or compare bread recipes.","do_not_use_when":"You want a ready-made pizza formula from ball count and weight (use pizza-dough) or plain servings-based scaling (use recipe-scaler).","required_inputs":["flour_g","ingredient_names"],"optional_inputs":["ingredient_percents","ingredient_grams"],"urls":{"html":"https://tttkmbb.com/food/bakers-percentage","markdown":"https://tttkmbb.com/food/bakers-percentage.md","schema":"https://tttkmbb.com/api/v1/calculators/bakers-percentage","api":"https://tttkmbb.com/api/v1/calculate/bakers-percentage"}},{"calculator_id":"turkey-cooking-time","entity_type":"calculator","name":"Turkey Cooking Time Calculator","category":"food","tool_name":"estimate_turkey_cooking_time","description":"Looks up the USDA FSIS roasting timetable for a whole turkey at 325 °F (163 °C) by weight and stuffing, returning the time range in minutes, the 165 °F (74 °C) safe internal temperature and refrigerator thawing time.","use_when":"You need to plan how long a turkey of a given weight takes to roast in a conventional oven and when to start thawing it.","do_not_use_when":"You are deep-frying, smoking, spatchcocking, cooking a turkey breast only over 8 lb, or roasting at a different oven temperature; the USDA table covers whole birds at 325 °F only.","required_inputs":["weight"],"optional_inputs":["weight_unit","stuffed","oven_temperature"],"urls":{"html":"https://tttkmbb.com/food/turkey-cooking-time","markdown":"https://tttkmbb.com/food/turkey-cooking-time.md","schema":"https://tttkmbb.com/api/v1/calculators/turkey-cooking-time","api":"https://tttkmbb.com/api/v1/calculate/turkey-cooking-time"}},{"calculator_id":"flooring","entity_type":"calculator","name":"Flooring Calculator","category":"construction","tool_name":"estimate_flooring_materials","description":"Computes the floor area of a rectangular room, adds a cutting-waste allowance and converts the result into the number of boxes to buy from the coverage printed on the packaging. Areas are reported in m² and ft².","use_when":"You need to order laminate, vinyl plank, hardwood, carpet tiles or underlay for a room and want the area with waste and the box count.","do_not_use_when":"You are counting individual tiles with grout joints (use tile), boards for an outdoor deck (use decking) or the room is L-shaped: split it into rectangles, run this for each and add the results (or use rectangle for the areas).","required_inputs":["room_length","room_width"],"optional_inputs":["unit_system","waste_percent","box_coverage"],"urls":{"html":"https://tttkmbb.com/construction/flooring","markdown":"https://tttkmbb.com/construction/flooring.md","schema":"https://tttkmbb.com/api/v1/calculators/flooring","api":"https://tttkmbb.com/api/v1/calculate/flooring"}},{"calculator_id":"paint","entity_type":"calculator","name":"Paint Calculator","category":"construction","tool_name":"estimate_paint_needed","description":"Estimates wall paint from the wall area (room length, width and height, or a given area), subtracting 1.9 m² per door and 1.4 m² per window, multiplying by the number of coats and dividing by the coverage rate; reports litres, US gallons and cans.","use_when":"You need to know how much paint to buy for the walls of a room or for a known wall area, in litres or gallons and cans.","do_not_use_when":"You need ceiling, floor or exterior siding paint with different coverage rates (enter the area and the product's coverage directly), or you need the wall area only (use rectangle).","required_inputs":[],"optional_inputs":["unit_system","room_length","room_width","wall_height","wall_area","doors","windows","coats","coverage","can_size"],"urls":{"html":"https://tttkmbb.com/construction/paint","markdown":"https://tttkmbb.com/construction/paint.md","schema":"https://tttkmbb.com/api/v1/calculators/paint","api":"https://tttkmbb.com/api/v1/calculate/paint"}},{"calculator_id":"concrete-slab","entity_type":"calculator","name":"Concrete Slab Calculator","category":"construction","tool_name":"estimate_concrete_slab","description":"Computes the concrete volume of a rectangular slab, footing or pad from length, width and thickness, adds a waste allowance and converts it to cubic yards, cubic feet and the number of 80 lb, 60 lb and 25 kg bags of premixed concrete.","use_when":"You need the amount of ready-mix concrete to order or the number of premix bags for a slab, patio, shed base, footing or pad of uniform thickness.","do_not_use_when":"The pour is a cylinder such as a post hole or pier (use cylinder for the volume), or you need mortar for brickwork (use brick).","required_inputs":["length","width","thickness"],"optional_inputs":["unit_system","waste_percent"],"urls":{"html":"https://tttkmbb.com/construction/concrete-slab","markdown":"https://tttkmbb.com/construction/concrete-slab.md","schema":"https://tttkmbb.com/api/v1/calculators/concrete-slab","api":"https://tttkmbb.com/api/v1/calculate/concrete-slab"}},{"calculator_id":"tile","entity_type":"calculator","name":"Tile Calculator","category":"construction","tool_name":"estimate_tiles_needed","description":"Counts the tiles needed for a floor or wall area from the tile dimensions plus the grout joint width, adds a cutting-waste allowance and converts to boxes when the tiles per box are known.","use_when":"You need to order ceramic, porcelain or stone tiles for a known area and tile size, including grout joints and waste.","do_not_use_when":"You are laying planks or sheet goods sold by area (use flooring), or need the area itself from room dimensions (use rectangle first).","required_inputs":["area","tile_length","tile_width"],"optional_inputs":["unit_system","grout_gap_mm","waste_percent","tiles_per_box"],"urls":{"html":"https://tttkmbb.com/construction/tile","markdown":"https://tttkmbb.com/construction/tile.md","schema":"https://tttkmbb.com/api/v1/calculators/tile","api":"https://tttkmbb.com/api/v1/calculate/tile"}},{"calculator_id":"roof-pitch","entity_type":"calculator","name":"Roof Pitch Calculator","category":"construction","tool_name":"calculate_roof_pitch","description":"Converts a roof slope given as rise and run, or as an angle, into the pitch expressed in rise per 12 units of run, the angle in degrees, the slope in percent and the rafter length multiplier (rafter length per unit of horizontal run).","use_when":"You need to convert between roof pitch notations (x:12, degrees, percent) or estimate rafter length from the horizontal run.","do_not_use_when":"You need a general right-triangle solution with all sides (use right-triangle) or a plain angle unit conversion (use angle).","required_inputs":[],"optional_inputs":["rise","run","angle_degrees","horizontal_run_length"],"urls":{"html":"https://tttkmbb.com/construction/roof-pitch","markdown":"https://tttkmbb.com/construction/roof-pitch.md","schema":"https://tttkmbb.com/api/v1/calculators/roof-pitch","api":"https://tttkmbb.com/api/v1/calculate/roof-pitch"}},{"calculator_id":"stairs","entity_type":"calculator","name":"Stair Calculator","category":"construction","tool_name":"calculate_stair_dimensions","description":"Divides a total floor-to-floor rise into equal risers close to a target riser height, derives the tread count, total run, stringer length and stair angle, and checks the result against the IRC residential limits (riser ≤ 7¾ in / 196 mm, tread ≥ 10 in / 254 mm) and the 2R + T comfort rule.","use_when":"You are laying out a straight flight of interior or deck stairs and need the number of risers, the exact riser height, the total run and the stringer length.","do_not_use_when":"The stair has winders, landings or curves (design each straight flight separately), or you need a roof/rafter slope (use roof-pitch).","required_inputs":["total_rise"],"optional_inputs":["unit_system","ideal_riser_height","tread_depth"],"urls":{"html":"https://tttkmbb.com/construction/stairs","markdown":"https://tttkmbb.com/construction/stairs.md","schema":"https://tttkmbb.com/api/v1/calculators/stairs","api":"https://tttkmbb.com/api/v1/calculate/stairs"}},{"calculator_id":"wallpaper","entity_type":"calculator","name":"Wallpaper Calculator","category":"construction","tool_name":"estimate_wallpaper_rolls","description":"Estimates wallpaper rolls by the strip method: the strip length is the wall height plus 10 cm trim, rounded up to a whole pattern repeat; whole strips per roll are counted, door and window areas are deducted and the strips are converted to rolls.","use_when":"You need to know how many rolls of wallpaper to buy for a room from its perimeter (or wall area), height and the roll dimensions, with or without a pattern repeat.","do_not_use_when":"You are painting (use paint) or boarding (use drywall) the walls, or the paper is a mural sold by the panel.","required_inputs":["wall_height"],"optional_inputs":["unit_system","room_perimeter","wall_area","doors","windows","roll_width","roll_length","pattern_repeat"],"urls":{"html":"https://tttkmbb.com/construction/wallpaper","markdown":"https://tttkmbb.com/construction/wallpaper.md","schema":"https://tttkmbb.com/api/v1/calculators/wallpaper","api":"https://tttkmbb.com/api/v1/calculate/wallpaper"}},{"calculator_id":"gravel","entity_type":"calculator","name":"Gravel Calculator","category":"construction","tool_name":"estimate_gravel_volume","description":"Computes the volume of loose aggregate needed to cover an area to a given depth and converts it to weight with a typical bulk density for gravel, crushed stone, sand, topsoil or mulch (or a custom density).","use_when":"You need to order gravel, crushed stone, sand, topsoil or bark mulch by volume (m³, yd³) or by weight (tonnes, US tons) for a driveway, path, bed or sub-base.","do_not_use_when":"The material is concrete (use concrete-slab) or you need the density of a specific product: use the supplier's figure via material = custom and density_t_per_m3.","required_inputs":["depth"],"optional_inputs":["unit_system","length","width","area","material","density_t_per_m3"],"urls":{"html":"https://tttkmbb.com/construction/gravel","markdown":"https://tttkmbb.com/construction/gravel.md","schema":"https://tttkmbb.com/api/v1/calculators/gravel","api":"https://tttkmbb.com/api/v1/calculate/gravel"}},{"calculator_id":"drywall","entity_type":"calculator","name":"Drywall Calculator","category":"construction","tool_name":"estimate_drywall_sheets","description":"Estimates the number of gypsum board sheets for walls (and optionally the ceiling) of a room with a waste allowance, plus screws at about one per square foot and joint compound at the USG rate of 10 gallons per 1,000 ft² of board.","use_when":"You need to order plasterboard/drywall sheets, screws and joint compound for a room or a known wall area.","do_not_use_when":"You need paint or wallpaper quantities for the finished wall (use paint or wallpaper), or metal-stud framing take-offs.","required_inputs":[],"optional_inputs":["unit_system","room_length","room_width","wall_height","wall_area","include_ceiling","openings_area","sheet_size","waste_percent"],"urls":{"html":"https://tttkmbb.com/construction/drywall","markdown":"https://tttkmbb.com/construction/drywall.md","schema":"https://tttkmbb.com/api/v1/calculators/drywall","api":"https://tttkmbb.com/api/v1/calculate/drywall"}},{"calculator_id":"fence","entity_type":"calculator","name":"Fence Calculator","category":"construction","tool_name":"estimate_fence_materials","description":"Estimates the posts, rails and pickets for a straight run of wooden fence from the total length, the maximum post spacing, the number and width of gates, the rails per section and the picket width plus gap.","use_when":"You need a material list (posts, rails, pickets) for a picket, privacy or post-and-rail fence of a known length.","do_not_use_when":"You need concrete for the post holes (use cylinder for the hole volume and concrete-slab for bags), or the fence is chain-link or panel fencing sold per panel (divide the length by the panel width instead).","required_inputs":["total_length"],"optional_inputs":["unit_system","post_spacing","gates","gate_width","rails_per_section","picket_width","picket_gap"],"urls":{"html":"https://tttkmbb.com/construction/fence","markdown":"https://tttkmbb.com/construction/fence.md","schema":"https://tttkmbb.com/api/v1/calculators/fence","api":"https://tttkmbb.com/api/v1/calculate/fence"}},{"calculator_id":"decking","entity_type":"calculator","name":"Decking Calculator","category":"construction","tool_name":"estimate_decking_materials","description":"Estimates the number of deck boards (rows of boards across the width, board lengths along the length, plus waste), the joists at a given spacing and the screws at two per board per joist for a rectangular deck.","use_when":"You need a material list for a rectangular timber or composite deck: boards, joists and fasteners.","do_not_use_when":"You need structural sizing of joists and beams (span tables depend on species, grade and load; see the AWC DCA 6 guide) or stairs to the deck (use stairs).","required_inputs":["deck_length","deck_width"],"optional_inputs":["unit_system","board_width","board_gap","board_length","joist_spacing","waste_percent"],"urls":{"html":"https://tttkmbb.com/construction/decking","markdown":"https://tttkmbb.com/construction/decking.md","schema":"https://tttkmbb.com/api/v1/calculators/decking","api":"https://tttkmbb.com/api/v1/calculate/decking"}},{"calculator_id":"board-feet","entity_type":"calculator","name":"Board Feet Calculator","category":"construction","tool_name":"calculate_board_feet","description":"Computes board feet (the US lumber volume unit: 1 board foot = 144 cubic inches = a 1 in × 12 in × 12 in board) from nominal thickness and width in inches and length in feet, for a given quantity, with the total cost at a price per board foot.","use_when":"You are pricing or ordering hardwood or rough lumber sold by the board foot, or converting lumber dimensions into board feet, cubic feet or cubic metres.","do_not_use_when":"Lumber is sold by the linear foot or piece (dimensional softwood such as 2 × 4 studs), or you need deck board counts (use decking).","required_inputs":["thickness_in","width_in","length_ft"],"optional_inputs":["quantity","price_per_board_foot"],"urls":{"html":"https://tttkmbb.com/construction/board-feet","markdown":"https://tttkmbb.com/construction/board-feet.md","schema":"https://tttkmbb.com/api/v1/calculators/board-feet","api":"https://tttkmbb.com/api/v1/calculate/board-feet"}},{"calculator_id":"brick","entity_type":"calculator","name":"Brick Calculator","category":"construction","tool_name":"estimate_bricks_needed","description":"Counts the bricks in a single-leaf (half-brick, stretcher-bond) wall from its length and height using a standard brick size with its mortar joint, adds waste, and estimates the mortar volume geometrically and the bags of mortar mix from a manufacturer rule of thumb.","use_when":"You need the number of bricks and the mortar for a garden wall, veneer or single-skin wall of known face area.","do_not_use_when":"The wall is concrete block (use the block face 440 × 215 mm or 8 × 16 in as a custom brick) or two leaves thick: double the brick count, or use concrete-slab for footings.","required_inputs":["wall_length","wall_height"],"optional_inputs":["unit_system","brick_size","brick_length","brick_height","brick_width","mortar_joint","waste_percent"],"urls":{"html":"https://tttkmbb.com/construction/brick","markdown":"https://tttkmbb.com/construction/brick.md","schema":"https://tttkmbb.com/api/v1/calculators/brick","api":"https://tttkmbb.com/api/v1/calculate/brick"}}]},"timestamp":"2026-09-23T23:23:50Z","next_actions":[],"links":{"docs":"https://tttkmbb.com/calculators.md"}}