# Health calculators

> Body metrics and nutrition: BMI, BMR, TDEE, body fat, ideal weight, macros, hydration, heart-rate zones, due date.

16 calculators. HTML index: https://tttkmbb.com/health · JSON: https://tttkmbb.com/api/v1/calculators?category=health

- [BMI Calculator](https://tttkmbb.com/health/bmi.md): 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. Tool: `calculate_bmi`.
- [BMR Calculator](https://tttkmbb.com/health/bmr.md): 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. Tool: `calculate_bmr`.
- [TDEE Calculator](https://tttkmbb.com/health/tdee.md): Estimates total daily energy expenditure from Mifflin-St Jeor BMR and an activity level, and derives calorie targets for maintaining, losing or gaining weight. Tool: `calculate_tdee`.
- [Body Fat Calculator](https://tttkmbb.com/health/body-fat.md): 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. Tool: `calculate_body_fat_percentage`.
- [Ideal Weight Calculator](https://tttkmbb.com/health/ideal-weight.md): 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. Tool: `calculate_ideal_weight`.
- [Water Intake Calculator](https://tttkmbb.com/health/water-intake.md): 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. Tool: `calculate_daily_water_intake`.
- [Calorie Deficit & Weight Loss Time Calculator](https://tttkmbb.com/health/calorie-deficit.md): 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. Tool: `calculate_calorie_deficit_timeline`.
- [Macro Calculator](https://tttkmbb.com/health/macros.md): 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. Tool: `calculate_macros`.
- [Heart Rate Zone Calculator](https://tttkmbb.com/health/heart-rate-zones.md): 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. Tool: `calculate_heart_rate_zones`.
- [Pregnancy Due Date Calculator](https://tttkmbb.com/health/pregnancy-due-date.md): Estimates the due date, conception date and current gestational age from the first day of the last menstrual period, adjusting for cycle length (Naegele's rule). Tool: `calculate_pregnancy_due_date`.
- [Ovulation Calculator](https://tttkmbb.com/health/ovulation.md): 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. Tool: `calculate_ovulation_date`.
- [Waist-to-Height Ratio Calculator](https://tttkmbb.com/health/waist-to-height-ratio.md): Divides waist circumference by height and classifies the ratio using the 'keep your waist to less than half your height' guidance (NICE 2022). Tool: `calculate_waist_to_height_ratio`.
- [Lean Body Mass Calculator](https://tttkmbb.com/health/lean-body-mass.md): Estimates lean body mass (fat-free mass) from weight, height and sex with the Boer (1984), James (1976) and Hume (1966) formulas. Tool: `calculate_lean_body_mass`.
- [Protein Intake Calculator](https://tttkmbb.com/health/protein-intake.md): 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. Tool: `calculate_protein_intake`.
- [Blood Pressure Category Calculator](https://tttkmbb.com/health/blood-pressure.md): 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. Tool: `classify_blood_pressure`.
- [Body Surface Area Calculator](https://tttkmbb.com/health/body-surface-area.md): Computes body surface area in square metres from height and weight using the Mosteller and Du Bois formulas, as used for chemotherapy and other weight-independent dosing. Tool: `calculate_body_surface_area`.