Health & Fitness Calculators
BMI, BMR, calorie, body fat, pregnancy, pace and other free health and fitness calculators based on trusted medical formulas.
Army Body Fat Calculator | US Army Circumference Method
An Army body fat calculator estimates body-fat percentage with the US Army circumference method from AR 600-9: log-transformed height, neck, waist (and hip for women) measurements. It outputs estimated body fat % and pass/fail against the Army's age- and sex-specific screening thresholds.
BAC Calculator | Estimate Blood Alcohol and Time to Zero
Estimate your blood alcohol concentration from drinks, body weight, sex and time elapsed, using the Widmark formula with the elimination rate explained. The result includes how long until your BAC returns to zero — essential for understanding when you are safe to drive (never drink and drive).
BMI Calculator | Measure BMI and See Weight Category
A BMI calculator measures Body Mass Index — your weight in kilograms divided by the square of your height in metres. It is a screening tool the WHO uses to flag potential underweight, overweight, or obesity in adults aged 20 and older. BMI does not measure body fat directly, so use it alongside waist circumference for a full picture.
BMR Calculator | Estimate Basal Metabolic Rate
Find the calories your body burns at complete rest using the Mifflin-St Jeor equation, then multiply by your activity level for your daily maintenance target. The foundation of every weight-loss and muscle-gain plan — enter your details and get your BMR and TDEE.
Body Fat Calculator | Estimate Body Fat Using Navy Method
Estimates body fat percentage using the U.S. Navy circumference method. Enter your sex, age, height, and the required measurements — neck and waist, plus hip for women — and the tool calculates your body fat percentage, then compares the result with the ACE classification ranges from essential to athlete levels.
Body Surface Area Calculator | Du Bois Formula
A body surface area (BSA) calculator estimates total body surface in square metres from weight and height. It uses the Du Bois formula BSA = 0.007184 × W^0.425 × H^0.725 — the most widely referenced BSA equation for chemotherapy dosing, GFR indexing and cardiac output normalisation.
Body Type Calculator | Identify Shape From Bust-Waist-Hip Ratios
Classifies your body shape from three measurements. Enter your bust, waist, and hip measurements in inches, and the tool compares the ratios between them to identify your shape — hourglass, pear, apple, rectangle, or inverted triangle — with style guidance for each category.
Calorie Calculator | Find Daily Calories For Weight Goals
Determines how many calories you should eat each day to hit your goal. Enter your age, sex, height, weight, and activity level, plus your goal of losing, maintaining, or gaining weight, and the tool computes your maintenance calories and a safe daily target using standard BMR and activity equations, with a recommended weekly rate of change.
Calories Burned Calculator | Estimate calories via METs
Estimate calories burned for walking, running, cycling and dozens of other activities using the MET formula, scaled by your body weight and duration. Plan workouts and balance your energy budget — the tool shows the burn for your exact weight and time.
Carbohydrate Calculator | Get daily carb grams from calories
Work out how many grams of carbohydrate you need each day from your calorie target and chosen carb percentage, with the 4 kcal-per-gram conversion shown. Build a low-carb, moderate or higher-carb plan that fits your goals.
Conception Calculator | Find conception and ovulation dates
Estimates when conception most likely occurred. Enter your due date, the first day of your last period, or an ultrasound date, and the tool works backwards using the standard 280-day pregnancy timeline to estimate the conception date and the likely date of ovulation for that cycle.
Fat Intake Calculator | Estimate Daily Fat Grams and Guidelines
Calculate your daily fat gram target from your calorie needs and the percentage of calories you want from fat, using the 9 kcal-per-gram conversion. See the healthy 20–35% range for your calorie level and plan your diet accordingly.
GFR Calculator | Estimate eGFR and Classify CKD Stage
Estimates kidney function using the 2021 CKD-EPI creatinine equation. Enter your serum creatinine, age, sex, and race, and the tool calculates your estimated glomerular filtration rate (eGFR) in mL/min/1.73 m², then classifies the result into the corresponding chronic kidney disease (CKD) stage.
Healthy Weight Calculator | Ideal Range by Height
A healthy weight calculator converts height into the weight range that keeps BMI between 18.5 and 24.9 — the WHO-recognized healthy band. Range = 18.5×h² to 24.9×h² with height in metres.
Lean Body Mass Calculator | Boer Formula
A lean body mass (LBM) calculator estimates fat-free mass from weight, height and sex using the Boer equations: men LBM = 0.407×W + 0.267×H − 19.2; women LBM = 0.252×W + 0.473×H − 48.3 (weight in kg, height in cm). LBM underlies protein requirements, anaesthetic dosing and metabolic rate estimates.
Macro Calculator | Split Daily Calories Into Protein, Carb, Fat
Set your daily protein, carbohydrate and fat gram targets from your calorie needs and chosen macro split. The tool estimates your calories from age, sex, height, weight and activity, then converts each macro percentage into exact grams — the framework for meal planning.
One-Rep-Max Calculator | Estimate 1RM and Training Percentages
Enter the weight you lifted and the number of reps you completed, and this 1RM calculator estimates your one-rep max using the Epley and Brzycki formulas, then prints a full training percentage table (55–95%) for programming your next sessions. It also lets you work backwards from a target 1RM to find the loads for each rep range.
Ovulation Calculator | Estimate Ovulation Date and Fertile Window
Predict your ovulation day and fertile window from the first day of your last period and cycle length, with the luteal-phase rule explained. Plan or avoid pregnancy with a clear view of your cycle — the calculator shows the fertile days for your next cycles.
Pace Calculator | Compute Pace, Speed, and Predicted Race Times
Convert run time and distance into pace per mile or kilometre, speed in mph or km/h, and finish-time projections. The essential tool for runners planning workouts, marathons and training paces.
Period Calculator | Predict Next Period Dates and Ovulation
Enter the first day of your last period and your average cycle length, and this calculator predicts your next period dates for the coming months, including estimated ovulation days. It also notes the difference between regular and irregular cycles and positions itself as a tracking aid rather than medical advice.
Pregnancy Calculator | Track Pregnancy Week, Due Date, Milestones
Estimate your due date from the last menstrual period or conception date, and track your current week, trimester and key milestones. The standard 40-week rule applied with clear dates — a planning companion for expecting parents (confirm with your provider).
Protein Calculator | Calculate Daily Protein And Per-Meal Targets
Find your daily protein target in grams from your body weight, activity level and goal — fat loss, muscle gain or maintenance. Uses the research-backed 0.7–1.0 g per pound range for active people and shows how to spread it across meals.
RIR Calculator | Estimate 1RM and Suggest Training Loads
Estimates your 1RM from a set's weight, reps and reps in reserve (RIR), then suggests training loads for common rep/RIR targets.
Sleep Cycle Calculator | Best Bedtime & Wake Times
A sleep cycle calculator recommends bedtimes for a chosen wake time by counting back in 90-minute sleep cycles. Six cycles (9 h) suits most adults, five (7.5 h) is the common target, and four (6 h) is the minimum for one night. Each result adds the average 15-minute sleep onset latency.
Steps to Miles Calculator | Convert steps to miles or km
Converts your step count into distance travelled. Enter your number of steps, height, and whether you walked or ran, and the tool estimates your stride length and computes the distance in miles or kilometres. It also shows how many steps typically make a mile at your height, so you can set daily walking targets.
Target Heart Rate Calculator | Estimate zones with Karvonen
Find the heart-rate zones for your training — fat burn, aerobic, threshold and maximum — using the Karvonen formula with your resting heart rate. Train at the right intensity for your goal, whether base endurance or hard intervals.
TDEE Calculator | Estimate Daily Maintenance Calories And Targets
Calculate your total daily energy expenditure — the calories you burn each day — from your BMR and activity level. The number every diet plan starts from: eat at maintenance to stay, below to lose, above to gain.
Waist-to-Hip Ratio Calculator | WHO Risk Chart
A waist-to-hip ratio (WHR) calculator divides waist circumference by hip circumference and classifies health risk using WHO thresholds: ≥0.96 (men) or ≥0.81 (women) indicates moderate risk, and ≥1.0 / ≥0.86 indicates high cardiometabolic risk from abdominal fat distribution.
Water Intake Calculator | Estimate Daily Water Intake
Estimate how much water you should drink each day from your weight, activity level, exercise and climate, with the standard hydration guidelines applied. The result shows cups, ounces and litres — a practical daily target for staying properly hydrated.