{"success":true,"version":"v1","request":{"tool":"list_calculators","category":"finance"},"result":{"entity_type":"calculator_list","status":"completed","count":46,"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 loan-payment).","required_inputs":["principal","annual_rate_percent","years"],"optional_inputs":["compounding_frequency","monthly_contribution"],"urls":{"html":"https://tttkmbb.com/finance/compound-interest","markdown":"https://tttkmbb.com/finance/compound-interest.md","schema":"https://tttkmbb.com/api/v1/calculators/compound-interest","api":"https://tttkmbb.com/api/v1/calculate/compound-interest"}},{"calculator_id":"simple-interest","entity_type":"calculator","name":"Simple Interest Calculator","category":"finance","tool_name":"calculate_simple_interest","description":"Computes interest that accrues only on the original principal (no compounding) over a term in years, and the resulting total amount.","use_when":"The agreement states simple, non-compounding interest, e.g. short-term personal loans, some bonds and statutory interest on late payments, or you want a quick estimate.","do_not_use_when":"Interest is reinvested or charged on accrued interest (use compound-interest), or you 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 loan.","do_not_use_when":"The loan is adjustable-rate or interest-only, or you only need the payment on a plain loan amount (use loan-payment).","required_inputs":["home_price","annual_rate_percent"],"optional_inputs":["down_payment","term_years","annual_property_tax","annual_home_insurance","monthly_hoa"],"urls":{"html":"https://tttkmbb.com/finance/mortgage-payment","markdown":"https://tttkmbb.com/finance/mortgage-payment.md","schema":"https://tttkmbb.com/api/v1/calculators/mortgage-payment","api":"https://tttkmbb.com/api/v1/calculate/mortgage-payment"}},{"calculator_id":"apy","entity_type":"calculator","name":"APY Calculator","category":"finance","tool_name":"convert_apr_to_apy","description":"Converts a nominal annual rate (APR) into the effective annual yield (APY) for a given compounding frequency, and reports the periodic rate and the one-year growth of 1,000.","use_when":"You want to compare deposit accounts or loans quoted with different compounding frequencies, or need the effective annual rate for a nominal rate.","do_not_use_when":"You need a balance after several years or with deposits (use compound-interest), or the account quotes an APY already and you want the nominal rate (enter it as annual compounding).","required_inputs":["apr_percent"],"optional_inputs":["compounding_frequency"],"urls":{"html":"https://tttkmbb.com/finance/apy","markdown":"https://tttkmbb.com/finance/apy.md","schema":"https://tttkmbb.com/api/v1/calculators/apy","api":"https://tttkmbb.com/api/v1/calculate/apy"}},{"calculator_id":"savings-goal","entity_type":"calculator","name":"Savings Goal Calculator","category":"finance","tool_name":"calculate_savings_goal_deposit","description":"Solves for the fixed end-of-month deposit required to grow current savings to a goal amount within a given number of years at a monthly-compounded annual rate.","use_when":"You know the target amount, the deadline and an expected return and want the monthly saving required (emergency fund, down payment, tuition).","do_not_use_when":"You already know the deposit and want the resulting balance (use compound-interest or future-value), or the contributions are irregular.","required_inputs":["goal_amount","years"],"optional_inputs":["current_savings","annual_rate_percent"],"urls":{"html":"https://tttkmbb.com/finance/savings-goal","markdown":"https://tttkmbb.com/finance/savings-goal.md","schema":"https://tttkmbb.com/api/v1/calculators/savings-goal","api":"https://tttkmbb.com/api/v1/calculate/savings-goal"}},{"calculator_id":"future-value","entity_type":"calculator","name":"Future Value Calculator","category":"finance","tool_name":"calculate_future_value","description":"Computes the future value of a present lump sum and, optionally, of a level payment made every compounding period (ordinary annuity or annuity due) at a constant rate.","use_when":"You need the textbook FV of a single amount and/or a series of equal payments, e.g. for finance coursework, retirement projections or 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 of an investment, project or marketing spend, optionally converted to a per-year rate for comparison across holding periods.","do_not_use_when":"There were multiple cash flows at different dates (that needs IRR/NPV), or you only need the growth rate between two values (use cagr).","required_inputs":["initial_investment","final_value"],"optional_inputs":["years"],"urls":{"html":"https://tttkmbb.com/finance/roi","markdown":"https://tttkmbb.com/finance/roi.md","schema":"https://tttkmbb.com/api/v1/calculators/roi","api":"https://tttkmbb.com/api/v1/calculate/roi"}},{"calculator_id":"cagr","entity_type":"calculator","name":"CAGR Calculator","category":"finance","tool_name":"calculate_cagr","description":"Computes the compound annual growth rate that turns a beginning value into an ending value over a number of years, together with the total return and growth multiple.","use_when":"You need a smoothed per-year growth rate for revenue, a portfolio, a population or any quantity measured at two points in time.","do_not_use_when":"You need to account for interim deposits or withdrawals (CAGR ignores cash flows; use a money-weighted return), or the period is under a year.","required_inputs":["beginning_value","ending_value","years"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/cagr","markdown":"https://tttkmbb.com/finance/cagr.md","schema":"https://tttkmbb.com/api/v1/calculators/cagr","api":"https://tttkmbb.com/api/v1/calculate/cagr"}},{"calculator_id":"inflation","entity_type":"calculator","name":"Inflation Calculator","category":"finance","tool_name":"estimate_inflation_impact","description":"Projects how an amount's cost rises and its purchasing power falls over a number of years at a constant annual inflation rate, using compound growth of the price level.","use_when":"You want to estimate what today's amount will cost in the future, or what a future sum is worth in today's money, from an assumed inflation rate.","do_not_use_when":"You need historical 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":"amortization-schedule","entity_type":"calculator","name":"Amortization Schedule Calculator","category":"finance","tool_name":"calculate_amortization_schedule","description":"Builds the amortization schedule of a fixed-rate loan: the level monthly payment, a year-by-year summary of principal, interest and balance, the first 12 monthly rows, and the interest and time saved by a fixed extra monthly payment.","use_when":"You need to see how each payment splits into principal and interest over the life of a mortgage or loan, the balance at the end of each year, or the effect of paying extra every month.","do_not_use_when":"You only need the payment amount (use loan-payment or mortgage-payment), or you know the payment and want the payoff time of a revolving balance (use debt-payoff).","required_inputs":["principal","annual_rate_percent"],"optional_inputs":["term_years","term_months","extra_monthly_payment","start_date"],"urls":{"html":"https://tttkmbb.com/finance/amortization-schedule","markdown":"https://tttkmbb.com/finance/amortization-schedule.md","schema":"https://tttkmbb.com/api/v1/calculators/amortization-schedule","api":"https://tttkmbb.com/api/v1/calculate/amortization-schedule"}},{"calculator_id":"car-loan","entity_type":"calculator","name":"Car Loan Calculator","category":"finance","tool_name":"calculate_car_loan","description":"Computes the amount financed for a vehicle purchase from price, sales tax, fees, down payment and trade-in, then the level monthly payment, total interest and total cost of the car over the loan.","use_when":"You are buying a car with an installment loan and want the monthly payment or the full cost including sales tax, dealer fees and a trade-in credit.","do_not_use_when":"You are leasing rather than buying (use car-lease), or you only have a loan amount and rate (use loan-payment).","required_inputs":["vehicle_price","annual_rate_percent"],"optional_inputs":["down_payment","trade_in_value","sales_tax_percent","term_months","fees","trade_in_reduces_tax"],"urls":{"html":"https://tttkmbb.com/finance/car-loan","markdown":"https://tttkmbb.com/finance/car-loan.md","schema":"https://tttkmbb.com/api/v1/calculators/car-loan","api":"https://tttkmbb.com/api/v1/calculate/car-loan"}},{"calculator_id":"car-lease","entity_type":"calculator","name":"Car Lease Calculator","category":"finance","tool_name":"calculate_car_lease_payment","description":"Computes a closed-end vehicle lease payment from the negotiated price, residual value, money factor (or APR) and term: the monthly depreciation, finance charge, base payment, payment with sales tax and the total cost of the lease.","use_when":"You are evaluating a car lease offer and want to check the monthly payment or convert the money factor to an APR.","do_not_use_when":"You are buying the car with a loan (use car-loan), or the lease is open-ended with a balloon purchase (different terms).","required_inputs":["msrp","negotiated_price","residual_percent"],"optional_inputs":["money_factor","apr_percent","term_months","down_payment","sales_tax_percent"],"urls":{"html":"https://tttkmbb.com/finance/car-lease","markdown":"https://tttkmbb.com/finance/car-lease.md","schema":"https://tttkmbb.com/api/v1/calculators/car-lease","api":"https://tttkmbb.com/api/v1/calculate/car-lease"}},{"calculator_id":"refinance-break-even","entity_type":"calculator","name":"Refinance Break-Even Calculator","category":"finance","tool_name":"calculate_refinance_break_even","description":"Compares the payment on the remaining term of a current loan with a new loan at a different rate and term, and reports the monthly saving, the months needed for savings to recoup closing costs, and the difference in total interest over the life of both loans.","use_when":"You are deciding whether refinancing a mortgage or other amortizing loan is worth its closing costs, given how long you expect to keep the loan.","do_not_use_when":"You want a cash-out refinance amount or an adjustable-rate comparison (this assumes fixed rates), or you only need a payment (use loan-payment).","required_inputs":["current_balance","current_rate_percent","remaining_term_months","new_rate_percent","new_term_months"],"optional_inputs":["closing_costs","finance_closing_costs"],"urls":{"html":"https://tttkmbb.com/finance/refinance-break-even","markdown":"https://tttkmbb.com/finance/refinance-break-even.md","schema":"https://tttkmbb.com/api/v1/calculators/refinance-break-even","api":"https://tttkmbb.com/api/v1/calculate/refinance-break-even"}},{"calculator_id":"rent-vs-buy","entity_type":"calculator","name":"Rent vs. Buy Calculator","category":"finance","tool_name":"compare_rent_vs_buy","description":"Compares the net cost of renting with the net cost of buying a home over a chosen number of years: rent with annual increases versus mortgage payments, property tax, maintenance, transaction costs and the opportunity cost of the upfront cash, net of the equity recovered when the home is sold.","use_when":"You want a first-order comparison of renting against buying for a given horizon, rate, appreciation and investment-return assumption.","do_not_use_when":"You need tax deductions, rent-controlled scenarios or month-by-month cash-flow modelling; the model is annual and simplified. For the mortgage payment alone use mortgage-payment.","required_inputs":["monthly_rent","home_price","down_payment","annual_rate_percent","years"],"optional_inputs":["rent_growth_percent","term_years","property_tax_percent","maintenance_percent","home_appreciation_percent","investment_return_percent","buying_closing_costs_percent","selling_costs_percent"],"urls":{"html":"https://tttkmbb.com/finance/rent-vs-buy","markdown":"https://tttkmbb.com/finance/rent-vs-buy.md","schema":"https://tttkmbb.com/api/v1/calculators/rent-vs-buy","api":"https://tttkmbb.com/api/v1/calculate/rent-vs-buy"}},{"calculator_id":"down-payment","entity_type":"calculator","name":"Down Payment Calculator","category":"finance","tool_name":"calculate_down_payment","description":"Converts a down payment given as an amount or a percentage of the home price into the loan amount and loan-to-value ratio, flags whether private mortgage insurance is likely (LTV above 80 %) and estimates its annual and monthly cost at a given PMI rate.","use_when":"You want to know how much you will borrow and whether PMI applies for a given home price and down payment, or how much more cash reaches 20 % down.","do_not_use_when":"You need the monthly mortgage payment (use mortgage-payment) or a savings plan to reach the down payment (use savings-goal).","required_inputs":["home_price"],"optional_inputs":["down_payment_amount","down_payment_percent","pmi_rate_percent"],"urls":{"html":"https://tttkmbb.com/finance/down-payment","markdown":"https://tttkmbb.com/finance/down-payment.md","schema":"https://tttkmbb.com/api/v1/calculators/down-payment","api":"https://tttkmbb.com/api/v1/calculate/down-payment"}},{"calculator_id":"debt-to-income","entity_type":"calculator","name":"Debt-to-Income Ratio Calculator","category":"finance","tool_name":"calculate_debt_to_income_ratio","description":"Computes the back-end debt-to-income ratio (all monthly debt payments including housing divided by gross monthly income) and the front-end ratio (housing payment alone), and compares them with the 28/36 guideline and the 43 % qualified-mortgage benchmark.","use_when":"You want to check whether a proposed mortgage or other loan fits typical lender DTI limits, or how much monthly debt capacity remains.","do_not_use_when":"You need to know how long it takes to pay a balance off (use debt-payoff), or the amount of a down payment (use down-payment).","required_inputs":["gross_monthly_income"],"optional_inputs":["monthly_debts","other_monthly_debt","housing_payment"],"urls":{"html":"https://tttkmbb.com/finance/debt-to-income","markdown":"https://tttkmbb.com/finance/debt-to-income.md","schema":"https://tttkmbb.com/api/v1/calculators/debt-to-income","api":"https://tttkmbb.com/api/v1/calculate/debt-to-income"}},{"calculator_id":"student-loan","entity_type":"calculator","name":"Student Loan Calculator","category":"finance","tool_name":"calculate_student_loan_payment","description":"Computes the monthly payment and total interest of a student loan under a standard (level) plan or an approximation of the US federal graduated plan, including interest that accrues during a grace period and is capitalized when repayment starts.","use_when":"You want the monthly payment, total cost or effect of a grace period for a fixed-rate student loan under standard or graduated repayment.","do_not_use_when":"The loan is income-driven (IBR, PAYE, SAVE), variable-rate, or you know the payment and want the payoff time (use debt-payoff).","required_inputs":["balance","annual_rate_percent"],"optional_inputs":["term_years","grace_months","interest_accrues_during_grace","repayment_plan"],"urls":{"html":"https://tttkmbb.com/finance/student-loan","markdown":"https://tttkmbb.com/finance/student-loan.md","schema":"https://tttkmbb.com/api/v1/calculators/student-loan","api":"https://tttkmbb.com/api/v1/calculate/student-loan"}},{"calculator_id":"retirement-savings","entity_type":"calculator","name":"Retirement Savings Calculator","category":"finance","tool_name":"project_retirement_savings","description":"Projects retirement savings from the current balance and a fixed monthly contribution compounded monthly at an assumed annual return until the retirement age, reports the result in today's money using an inflation rate, and the income it supports at a 4 % withdrawal rate.","use_when":"You want to estimate what your savings will grow to by retirement, how much of that is contributions versus growth, and what it is worth in today's purchasing power.","do_not_use_when":"You need the amount required to retire (use fire-number), how long a balance lasts in retirement (use savings-withdrawal), or contributions that change over time.","required_inputs":["current_age","retirement_age"],"optional_inputs":["current_savings","monthly_contribution","annual_return_percent","annual_inflation_percent"],"urls":{"html":"https://tttkmbb.com/finance/retirement-savings","markdown":"https://tttkmbb.com/finance/retirement-savings.md","schema":"https://tttkmbb.com/api/v1/calculators/retirement-savings","api":"https://tttkmbb.com/api/v1/calculate/retirement-savings"}},{"calculator_id":"fire-number","entity_type":"calculator","name":"FIRE Number Calculator","category":"finance","tool_name":"calculate_fire_number","description":"Computes the portfolio needed to fund annual expenses at a safe withdrawal rate (the FIRE number, 25× expenses at 4 %), your progress towards it, and the years until current savings plus annual saving reach it at an assumed return.","use_when":"You want to know how much you need to retire early or become financially independent, and how many years of saving at your current rate it will take.","do_not_use_when":"You want to project a balance to a fixed retirement age (use retirement-savings) or test how long a balance lasts (use savings-withdrawal).","required_inputs":["annual_expenses"],"optional_inputs":["withdrawal_rate_percent","current_savings","annual_savings","annual_income","savings_rate_percent","annual_return_percent","current_age"],"urls":{"html":"https://tttkmbb.com/finance/fire-number","markdown":"https://tttkmbb.com/finance/fire-number.md","schema":"https://tttkmbb.com/api/v1/calculators/fire-number","api":"https://tttkmbb.com/api/v1/calculate/fire-number"}},{"calculator_id":"savings-withdrawal","entity_type":"calculator","name":"Savings Withdrawal Calculator","category":"finance","tool_name":"calculate_savings_withdrawal","description":"Given a balance earning a monthly-compounded return, computes how many months a fixed monthly withdrawal lasts (and the total withdrawn and interest earned), or the level monthly withdrawal that exhausts the balance over a chosen number of years, plus the interest-only withdrawal that preserves the balance forever.","use_when":"You are drawing down savings, a retirement account or an inheritance and want either the depletion date for a given withdrawal or the affordable withdrawal for a given period.","do_not_use_when":"You want the required portfolio for a withdrawal rate (use fire-number) or are still accumulating (use retirement-savings or compound-interest).","required_inputs":["balance","annual_return_percent"],"optional_inputs":["monthly_withdrawal","years"],"urls":{"html":"https://tttkmbb.com/finance/savings-withdrawal","markdown":"https://tttkmbb.com/finance/savings-withdrawal.md","schema":"https://tttkmbb.com/api/v1/calculators/savings-withdrawal","api":"https://tttkmbb.com/api/v1/calculate/savings-withdrawal"}},{"calculator_id":"npv","entity_type":"calculator","name":"NPV Calculator","category":"finance","tool_name":"calculate_npv","description":"Discounts a series of end-of-period cash flows at a required rate of return, subtracts the initial investment and reports the net present value, the present value of each cash flow and the profitability index.","use_when":"You are appraising a project or investment with an upfront cost followed by periodic cash flows and want to know whether it creates value at a given discount rate.","do_not_use_when":"You want the rate that makes NPV zero (use irr), the time to recover the outlay (use payback-period), or a single future amount (use present-value).","required_inputs":["discount_rate_percent","initial_investment","cash_flows"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/npv","markdown":"https://tttkmbb.com/finance/npv.md","schema":"https://tttkmbb.com/api/v1/calculators/npv","api":"https://tttkmbb.com/api/v1/calculate/npv"}},{"calculator_id":"irr","entity_type":"calculator","name":"IRR Calculator","category":"finance","tool_name":"calculate_irr","description":"Solves numerically for the discount rate at which the net present value of an initial investment and its subsequent cash flows equals zero, and reports the undiscounted gain and the number of sign changes (a warning for multiple IRRs).","use_when":"You want the annualized (per-period) return implied by an investment's cash-flow pattern, e.g. to compare projects or check a fund's stated return.","do_not_use_when":"Cash flows change sign more than once (multiple IRRs may exist; use npv at your hurdle rate), or there are only two values (use cagr).","required_inputs":["initial_investment","cash_flows"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/irr","markdown":"https://tttkmbb.com/finance/irr.md","schema":"https://tttkmbb.com/api/v1/calculators/irr","api":"https://tttkmbb.com/api/v1/calculate/irr"}},{"calculator_id":"payback-period","entity_type":"calculator","name":"Payback Period Calculator","category":"finance","tool_name":"calculate_payback_period","description":"Computes how long an investment takes to recover its initial outlay from a list of periodic cash flows or a constant annual cash flow, both undiscounted (simple payback) and discounted at a given rate (discounted payback), interpolating within the recovery period.","use_when":"You want a quick liquidity/risk measure of a project: the years until cumulative cash inflows equal the initial investment.","do_not_use_when":"You need the value created over the whole life (use npv) or the rate of return (use irr); payback ignores cash flows after recovery.","required_inputs":["initial_investment"],"optional_inputs":["cash_flows","annual_cash_flow","years","discount_rate_percent"],"urls":{"html":"https://tttkmbb.com/finance/payback-period","markdown":"https://tttkmbb.com/finance/payback-period.md","schema":"https://tttkmbb.com/api/v1/calculators/payback-period","api":"https://tttkmbb.com/api/v1/calculate/payback-period"}},{"calculator_id":"depreciation","entity_type":"calculator","name":"Depreciation Calculator","category":"finance","tool_name":"calculate_depreciation","description":"Computes an asset's depreciation expense for a chosen year, the accumulated depreciation and the book value, plus the full year-by-year schedule, using the straight-line, 150 % declining-balance, double-declining-balance or sum-of-the-years'-digits method.","use_when":"You need book (financial-statement) depreciation of equipment, vehicles or buildings over their useful life, or want to compare accelerated methods with straight-line.","do_not_use_when":"You need US tax depreciation under MACRS with its conventions and class lives (IRS Publication 946 tables), or units-of-production depreciation.","required_inputs":["cost","useful_life_years"],"optional_inputs":["salvage_value","method","year"],"urls":{"html":"https://tttkmbb.com/finance/depreciation","markdown":"https://tttkmbb.com/finance/depreciation.md","schema":"https://tttkmbb.com/api/v1/calculators/depreciation","api":"https://tttkmbb.com/api/v1/calculate/depreciation"}},{"calculator_id":"bond-yield","entity_type":"calculator","name":"Bond Yield Calculator","category":"finance","tool_name":"calculate_bond_yield","description":"Computes a bond's current yield and solves numerically for its yield to maturity from face value, coupon rate, market price, years to maturity and coupon frequency, and reports total coupon income and total return if held to maturity.","use_when":"You know a bond's price and coupon and want its yield to maturity (the annualized return if held to redemption) or want to compare bonds trading at different prices.","do_not_use_when":"The bond is callable, floating-rate or amortizing (yield to call / worst differ), or you want the price from a yield (invert with present-value style discounting).","required_inputs":["coupon_rate_percent","price","years_to_maturity"],"optional_inputs":["face_value","payments_per_year"],"urls":{"html":"https://tttkmbb.com/finance/bond-yield","markdown":"https://tttkmbb.com/finance/bond-yield.md","schema":"https://tttkmbb.com/api/v1/calculators/bond-yield","api":"https://tttkmbb.com/api/v1/calculate/bond-yield"}},{"calculator_id":"dividend-yield","entity_type":"calculator","name":"Dividend Yield Calculator","category":"finance","tool_name":"calculate_dividend_yield","description":"Computes the dividend yield and annual income of a shareholding from the share price and the annual (or quarterly) dividend per share, and projects the holding's value and income after a number of years with dividends reinvested at a constant yield and dividend growth rate.","use_when":"You want the yield of a stock or fund, the income from a given number of shares, or a projection of reinvested dividends over time.","do_not_use_when":"You need the profit from selling shares (use stock-profit) or a total-return comparison between two prices (use cagr).","required_inputs":["share_price"],"optional_inputs":["annual_dividend_per_share","quarterly_dividend_per_share","shares","dividend_growth_percent","years"],"urls":{"html":"https://tttkmbb.com/finance/dividend-yield","markdown":"https://tttkmbb.com/finance/dividend-yield.md","schema":"https://tttkmbb.com/api/v1/calculators/dividend-yield","api":"https://tttkmbb.com/api/v1/calculate/dividend-yield"}},{"calculator_id":"emi","entity_type":"calculator","name":"EMI Calculator","category":"finance","tool_name":"calculate_emi","description":"Computes the equated monthly instalment (EMI) of a home, car or personal loan from the loan amount, annual interest rate and tenure in months, with the total interest and total amount payable; identical to the standard amortizing-loan payment formula.","use_when":"You want the EMI for a loan quoted with an annual rate and a tenure in months, as is customary in India and other markets that use the EMI term.","do_not_use_when":"You need the year-by-year breakdown (use amortization-schedule), or a flat-rate loan where interest is charged on the original principal for the whole term (multiply principal × flat rate × years instead).","required_inputs":["loan_amount","annual_rate_percent","tenure_months"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/finance/emi","markdown":"https://tttkmbb.com/finance/emi.md","schema":"https://tttkmbb.com/api/v1/calculators/emi","api":"https://tttkmbb.com/api/v1/calculate/emi"}},{"calculator_id":"stock-profit","entity_type":"calculator","name":"Stock Profit Calculator","category":"finance","tool_name":"calculate_stock_profit","description":"Computes the profit or loss on a share trade from buy and sell prices, number of shares, commissions on each side and an optional capital-gains tax rate, with the percentage return on the total cost and the sell price needed to break even.","use_when":"You want to know what you made (or lost) on a stock sale after fees and tax, or the price at which a position becomes profitable.","do_not_use_when":"You want dividend income or reinvestment (use dividend-yield), an annualized return over the holding period (use roi or cagr), or tax lots with different purchase dates.","required_inputs":["buy_price","sell_price","shares"],"optional_inputs":["buy_commission","sell_commission","capital_gains_tax_percent"],"urls":{"html":"https://tttkmbb.com/finance/stock-profit","markdown":"https://tttkmbb.com/finance/stock-profit.md","schema":"https://tttkmbb.com/api/v1/calculators/stock-profit","api":"https://tttkmbb.com/api/v1/calculate/stock-profit"}},{"calculator_id":"loan-comparison","entity_type":"calculator","name":"Loan Comparison Calculator","category":"finance","tool_name":"compare_loans","description":"Compares two fixed-rate, fully amortizing loan offers for the same amount: the level monthly payment, total interest, up-front fees and total cost (interest + fees) of each, and which offer costs less over its full term.","use_when":"You have two loan or mortgage quotes with different rates, terms or fees for the same amount and want the payments and lifetime costs side by side.","do_not_use_when":"You are replacing an existing loan (use refinance-break-even), only need one loan's payment (use loan-payment), or will sell or repay early (this compares full-term costs and ignores the time value of money). Informational; not financial advice.","required_inputs":["loan_amount","rate_a_percent","term_a_years","rate_b_percent","term_b_years"],"optional_inputs":["fees_a","fees_b"],"urls":{"html":"https://tttkmbb.com/finance/loan-comparison","markdown":"https://tttkmbb.com/finance/loan-comparison.md","schema":"https://tttkmbb.com/api/v1/calculators/loan-comparison","api":"https://tttkmbb.com/api/v1/calculate/loan-comparison"}},{"calculator_id":"balloon-loan","entity_type":"calculator","name":"Balloon Loan Calculator","category":"finance","tool_name":"calculate_balloon_loan","description":"Computes the payments of a balloon loan: the monthly payment amortized over the full amortization period, the lump-sum balance (balloon) due when the loan matures early, and the total paid and interest up to and including the balloon.","use_when":"You need the monthly payment and final lump sum of a mortgage, commercial or auto loan whose payments are based on a long amortization but which must be repaid or refinanced after a shorter term.","do_not_use_when":"The loan is fully amortized over its term (use loan-payment or amortization-schedule), or payments are interest-only before the lump sum (use interest-only-loan). Informational; not financial advice.","required_inputs":["loan_amount","interest_rate_percent","balloon_after_years"],"optional_inputs":["amortization_years"],"urls":{"html":"https://tttkmbb.com/finance/balloon-loan","markdown":"https://tttkmbb.com/finance/balloon-loan.md","schema":"https://tttkmbb.com/api/v1/calculators/balloon-loan","api":"https://tttkmbb.com/api/v1/calculate/balloon-loan"}},{"calculator_id":"interest-only-loan","entity_type":"calculator","name":"Interest-Only Loan Calculator","category":"finance","tool_name":"calculate_interest_only_loan","description":"Computes the payments of an interest-only loan: the interest-only monthly payment during the initial period, the higher amortizing payment that repays the full principal over the remaining term, the interest paid in each phase and the extra cost versus a fully amortizing loan.","use_when":"You need the monthly payment during and after the interest-only period of a mortgage or HELOC-style loan, the payment jump at the end of the IO period, or the total interest of the structure.","do_not_use_when":"The loan amortizes from the first payment (use loan-payment), or the principal is due as a lump sum instead of being amortized after the IO period (use balloon-loan). Informational; not financial advice.","required_inputs":["loan_amount","interest_rate_percent","interest_only_years"],"optional_inputs":["total_term_years"],"urls":{"html":"https://tttkmbb.com/finance/interest-only-loan","markdown":"https://tttkmbb.com/finance/interest-only-loan.md","schema":"https://tttkmbb.com/api/v1/calculators/interest-only-loan","api":"https://tttkmbb.com/api/v1/calculate/interest-only-loan"}},{"calculator_id":"early-payment-discount","entity_type":"calculator","name":"Early Payment Discount Calculator","category":"finance","tool_name":"calculate_early_payment_discount","description":"Evaluates cash-discount payment terms such as 2/10 net 30: the discount on an invoice, the amount due if paid early, and the annualized simple and effective interest rate implied by forgoing the discount (the cost of trade credit).","use_when":"A supplier offers a percentage discount for paying an invoice within a few days and you want the annualized return of paying early, or whether borrowing to take the discount is worthwhile.","do_not_use_when":"You need a plain price reduction without payment terms (use discount), or a late-payment penalty or interest charge. Informational; not financial advice.","required_inputs":[],"optional_inputs":["discount_percent","discount_days","net_days","invoice_amount","borrowing_rate_percent"],"urls":{"html":"https://tttkmbb.com/finance/early-payment-discount","markdown":"https://tttkmbb.com/finance/early-payment-discount.md","schema":"https://tttkmbb.com/api/v1/calculators/early-payment-discount","api":"https://tttkmbb.com/api/v1/calculate/early-payment-discount"}},{"calculator_id":"budget-50-30-20","entity_type":"calculator","name":"50/30/20 Budget Calculator","category":"finance","tool_name":"calculate_50_30_20_budget","description":"Splits monthly after-tax income into needs, wants and savings/debt repayment with the 50/30/20 rule (Warren & Tyagi, All Your Worth, 2005) or custom percentages, and compares the targets with current spending when it is given.","use_when":"You want target amounts for essentials, discretionary spending and savings from take-home pay, or to check how far current spending deviates from the 50/30/20 split.","do_not_use_when":"You need the time or deposit to reach a savings target (use savings-goal), a debt payoff schedule (use debt-payoff), or a line-item budget. Informational; not financial advice.","required_inputs":["monthly_after_tax_income"],"optional_inputs":["needs_percent","wants_percent","savings_percent","current_needs","current_wants","current_savings"],"urls":{"html":"https://tttkmbb.com/finance/budget-50-30-20","markdown":"https://tttkmbb.com/finance/budget-50-30-20.md","schema":"https://tttkmbb.com/api/v1/calculators/budget-50-30-20","api":"https://tttkmbb.com/api/v1/calculate/budget-50-30-20"}},{"calculator_id":"net-worth","entity_type":"calculator","name":"Net Worth Calculator","category":"finance","tool_name":"calculate_net_worth","description":"Adds up assets (cash, investments, retirement accounts, real estate, vehicles, other) and liabilities (mortgage, student, car and credit-card debt, other) to give net worth, liquid net worth and the debt-to-asset ratio.","use_when":"You want a personal balance sheet: what is owned minus what is owed, how much of it is liquid, and how leveraged the household is.","do_not_use_when":"You need monthly cash-flow ratios such as debt-to-income (use debt-to-income), or valuations of the assets themselves. Informational; not financial advice.","required_inputs":[],"optional_inputs":["cash_and_savings","investments","retirement_accounts","real_estate","vehicles","other_assets","mortgage_balance","student_loans","car_loans","credit_card_debt","other_debts"],"urls":{"html":"https://tttkmbb.com/finance/net-worth","markdown":"https://tttkmbb.com/finance/net-worth.md","schema":"https://tttkmbb.com/api/v1/calculators/net-worth","api":"https://tttkmbb.com/api/v1/calculate/net-worth"}},{"calculator_id":"superannuation-guarantee","entity_type":"calculator","name":"Superannuation Guarantee Calculator","category":"finance","tool_name":"calculate_superannuation_guarantee","description":"Computes the compulsory employer superannuation guarantee (SG) contribution in Australia from ordinary time earnings (OTE), the SG rate (12 % from 1 July 2025) and the maximum contribution base, for a salary either excluding super or quoted as a package including super.","use_when":"You need the employer super an Australian salary attracts per pay period, quarter or year, the base salary inside a package quoted inclusive of super, or whether the quarterly maximum contribution base caps the contribution.","do_not_use_when":"You need salary-sacrifice or personal contribution tax effects, contribution-cap or Division 293 calculations, or super for another country's pension system. Rates are published constants that change each financial year; informational, not financial or tax advice.","required_inputs":["ordinary_time_earnings"],"optional_inputs":["pay_period","sg_rate_percent","maximum_contribution_base_per_quarter","include_in_package"],"urls":{"html":"https://tttkmbb.com/finance/superannuation-guarantee","markdown":"https://tttkmbb.com/finance/superannuation-guarantee.md","schema":"https://tttkmbb.com/api/v1/calculators/superannuation-guarantee","api":"https://tttkmbb.com/api/v1/calculate/superannuation-guarantee"}}]},"timestamp":"2026-09-25T01:11:28Z","next_actions":[],"links":{"docs":"https://tttkmbb.com/calculators.md"}}