Fitness and Health Calculators
Body metrics, calorie and macro targets, training, and pregnancy/cycle tracking tools — browse by topic or search below.
28 calculators in this category
Showing all 28 calculators
Body Composition & Weight
Measure body mass, fat, lean mass, and weight ranges from height and body measurements.
- BMI CalculatorCalculate your Body Mass Index (BMI) using the CDC-standard weight(kg) / height(m)² formula. Enter height and weight in metric or US units to get your BMI and, for adults 20+, the CDC weight category.
- Body Fat CalculatorEstimate your body fat percentage using the US Navy circumference method. Enter your sex, height, and neck/waist (and hip, for women) circumference measurements to get an instant estimate — no scale or caliper needed.
- Lean Body Mass CalculatorEstimate lean body mass using three established anthropometric formulas — Boer, James, and Hume. Enter height, weight, and sex to see each formula's estimate in kg and as a percentage of body weight.
- Ideal Weight CalculatorEstimate reference body weight using four established formulas — Devine, Robinson, Miller, and Hamwi. Enter height and sex to see each formula's estimate in kg and lb.
- Healthy Weight CalculatorCalculate a reference healthy-weight range for your height, based on the CDC's adult healthy BMI range (18.5–24.9). Enter your height in metric or US units to see the lower and upper weight bounds in kg and lb.
- Overweight CalculatorCalculate how many pounds or kilograms your current weight is above the CDC's BMI 25.0 category boundary for your height. Enter height, weight, and age in metric or US units.
- Low BMI Reference CalculatorCalculate your BMI and see the WHO underweight severity reference band (mild, moderate, or severe thinness) for adults. This is a descriptive reference, not a diagnosis of anorexia or any eating disorder.
- Army Body Composition CalculatorCalculate the current U.S. Army waist-to-height ratio (WHtR) body composition threshold. Enter waist circumference and height in the same unit to see your ratio and whether it is under the current 0.55 threshold.
- Body Surface Area (BSA) CalculatorCalculate body surface area (BSA) in square meters from height and weight, using the Mosteller and Du Bois formulas.
Calories & Nutrition
Set daily energy and macronutrient targets from your metabolism and activity level.
- BMR CalculatorEstimate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor and Harris-Benedict (revised) equations. Enter age, sex, height, and weight to see your estimated resting daily calorie burn.
- TDEE CalculatorEstimate your Total Daily Energy Expenditure (TDEE) — the maintenance calories you burn per day including activity — using the Mifflin-St Jeor BMR formula and a standard 5-tier activity multiplier.
- Calorie CalculatorEstimate your daily maintenance calories (TDEE) plus conservative mild weight-loss and mild weight-gain targets, built on the verified Mifflin-St Jeor BMR formula and standard activity multipliers.
- Macro CalculatorCalculate daily carbohydrate, protein, and fat gram targets from your daily calorie target and macro percentage split, using standard 4/4/9 kcal-per-gram energy conversion.
- Protein CalculatorCalculate a daily protein intake reference range in grams/day from your body weight and activity goal (sedentary, endurance, or muscle hypertrophy), based on published sports-nutrition guidelines.
- Carbohydrate CalculatorCalculate your daily carbohydrate calories and grams from your daily calorie allowance and carbohydrate percentage, using the standard 4 kcal-per-gram Atwater factor.
- Fat Intake CalculatorCalculate your daily dietary fat allowance in grams and calories from your daily calorie target and a chosen fat percentage, using the standard 9 kcal-per-gram Atwater energy factor.
Training & Activity
Plan workouts with strength, pace, heart-rate, and calories-burned estimates.
- One Rep Max CalculatorEstimate your one-rep max (1RM) from any weight and rep count between 1 and 12 using the Epley and Brzycki formulas — get both estimates plus a combined training number.
- Pace CalculatorCalculate your running pace per kilometer and per mile, plus speed in km/h and mph, from a distance and elapsed time.
- Calories Burned CalculatorEstimate calories burned during exercise using verified MET (metabolic equivalent) values for walking, running, cycling, and swimming, based on your body weight and session duration.
- Target Heart Rate CalculatorCalculate your Karvonen-method target heart rate training zones (Zone 1 Recovery through Zone 5 Maximum, with neutral Zone 2-4 labels) from your age and resting heart rate.
Pregnancy & Cycle
Estimate due dates, fertile windows, cycle timing, and recommended pregnancy weight gain.
- Ovulation CalculatorEstimate your predicted ovulation date and peak fertility window from the first day of your last period and your average cycle length.
- Period CalculatorPredict your next expected period start date (and the two cycles after it) from your last period's start date and typical cycle length.
- Due Date CalculatorEstimate your due date from the first day of your last menstrual period and average cycle length, using the modified Naegele's rule, with a calendar-only milestone timeline.
- Pregnancy CalculatorEstimate your due date, current gestational week, and trimester from the first day of your last menstrual period, average cycle length, and a reference date.
- Pregnancy Conception CalculatorEstimate your probable conception date window from an estimated due date, derived from the same formulas as the Due Date and Ovulation calculators.
- Pregnancy Weight Gain CalculatorEstimate a recommended pregnancy weight-gain reference range from your pre-pregnancy BMI, gestational week, and singleton or twin pregnancy, based on the IOM/National Academies 2009 guidelines.
Health Reference Metrics
Reference estimates for kidney function and blood alcohol content. Not medical advice.
- GFR CalculatorEstimate your Glomerular Filtration Rate (eGFR) using the race-free 2021 CKD-EPI creatinine equation. Enter serum creatinine (mg/dL), age, and biological sex — adults 18 and older.
- BAC Estimate CalculatorEstimate blood alcohol content (BAC) from actual drink volume, ABV, body weight, and elapsed time using the Widmark equation. Estimate only — not a breath or blood test, and not a driving-safety determination.
Guides for this category
Plain-English explanations of the formulas behind these calculators.