Health & Fitness Tools

Free health and fitness calculators — BMI, BMR and TDEE, body fat, ideal weight, macros, running pace, heart-rate zones and more. Provided for general information only, not medical advice. BAC estimates cannot tell you whether it is safe to drive.

Food, hydration and energy estimates

BMR & TDEE Calculator

Estimate your daily calorie needs (BMR and TDEE) using the Mifflin-St Jeor equation.

Water Intake Calculator

Estimate your daily water needs in liters and cups from weight and exercise time.

Macro Calculator

Split your daily calories into grams of protein, carbs and fat from a ratio preset.

Protein Intake Calculator

Get a daily protein target in grams from your body weight, goal and meal count.

Keto Macro Calculator

Calculate ketogenic-diet macros: calories, fat, protein and a net-carb cap from your stats.

Calorie Deficit & Weight-Loss Timeline Calculator

Estimate your maintenance calories, a safe daily deficit and target intake, then project a weight-loss timeline or goal date.

Intermittent Fasting Window Calculator

Get your exact eating and fasting windows for 16:8, 18:6, 20:4, OMAD or a custom protocol.

Training and activity estimates

Running Pace Calculator

Calculate running pace, time or distance, with pace per km and per mile and speed.

Heart Rate Zones

Find your max heart rate and the five training zones from your age and resting rate.

One Rep Max Calculator

Estimate your one-rep max from a lift and see training percentages from 95% to 60%.

Calories Burned Calculator

Estimate calories burned for an activity from its MET value, your weight and duration.

Race Time Predictor

Predict 5K, 10K, half and full marathon finish times from one recent race using the Riegel formula.

VO2 Max Calculator

Estimate VO2 max from a Cooper 12-minute run or from your resting and maximum heart rate.

Wilks & DOTS Calculator

Calculate your Wilks and DOTS powerlifting scores from bodyweight and total, in kg or lb, to compare strength across weight classes.

Body measurements and ratios

Body Fat Calculator

Estimate your body fat percentage using the US Navy circumference method.

Ideal Weight Calculator

Estimate ideal body weight from height using the Devine, Robinson, Miller and Hamwi formulas.

Lean Body Mass Calculator

Estimate lean body mass and fat mass from your height and weight using the Boer formula.

Waist-to-Hip Ratio

Compute your waist-to-hip ratio and the matching WHO health-risk category.

Body Surface Area Calculator

Calculate body surface area (m²) with the Mosteller, Du Bois, Haycock and Gehan–George formulas.

Waist-to-Height Ratio Calculator

Check your waist-to-height ratio against the 'keep your waist below half your height' health rule.

FFMI Calculator

Work out your Fat-Free Mass Index (FFMI) and height-normalized FFMI from weight, height and body-fat %.

Bra Size Calculator

Convert your underbust and bust measurements into a bra size with US, UK and EU equivalents plus sister sizes.

Cycle and pregnancy date estimates

Pregnancy Due Date

Estimate a due date from your last period using Naegele's rule, adjusted for cycle length.

Ovulation Calculator

Estimate your ovulation day and 6-day fertile window for the next three cycles.

Pregnancy Week Calculator

Find your current pregnancy week, trimester and due date from LMP, conception or IVF transfer date.

Period / Menstrual Cycle Calculator

Predict your next three period dates, estimated ovulation day and fertile window from your last period and cycle length.

Pregnancy Weight Gain Calculator

Find your recommended pregnancy weight-gain range from pre-pregnancy BMI, using the IOM/NASEM guidelines for a singleton or twins.

Conception Date Calculator

Estimate the conception date and fertile window from a due date, last menstrual period (LMP) or birth date, with the gestational reference.

Health and growth reference calculators

A1C to Glucose Converter

Convert HbA1c to estimated average glucose (mg/dL and mmol/L) and IFCC mmol/mol, both ways.

Blood Pressure Category Checker

Classify a blood pressure reading under both the US ACC/AHA and European ESC/ESH tables.

Child BMI Percentile Calculator

Find a child's BMI percentile and z-score for age and sex using the WHO 5–19 y growth reference.

Child Height Predictor

Predict a child's adult height from the parents' heights with the mid-parental (Tanner) method.

Child Blood Type Predictor

Predict a baby's possible ABO and Rh blood types from both parents' types, with the probability of each and which types cannot occur.

eGFR Calculator (CKD-EPI 2021)

Estimate kidney function (eGFR) from serum creatinine, age and sex using the race-free 2021 CKD-EPI equation, with the CKD stage.

Alcohol, smoking and caffeine estimates

Blood Alcohol (BAC) Estimator

Estimate blood alcohol content from drinks, weight and time using the Widmark formula.

Smoking Cost Calculator

See how much smoking costs you per day, week, month, year and over ten years.

Caffeine Half-Life Calculator

See how much caffeine remains in your body hour by hour and when you'll drop under 100 mg.

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