Health & Fitness Calculators

Calculate body mass index in metric or imperial units — WHO categories for adults, or CDC growth-chart percentiles for children and teens aged 2–19.

Estimate body fat percentage from tape measurements using the US Navy method, with lean mass and category comparison.

Compare four published ideal-weight formulas — Devine, Robinson, Miller and Hamwi — alongside the healthy BMI range for your height.

Estimate lean body mass and fat mass using the Boer, James and Hume equations, with the fat-free mass index.

Estimate your skeletal frame size — small, medium or large — from your height and wrist circumference.

Calculate your waist-to-height ratio against the simple "keep your waist under half your height" boundary.

Calculate your waist-to-hip ratio and see which WHO risk category it falls into — a measure of fat distribution that BMI cannot capture.

Estimate your basal metabolic rate — the energy your body uses at complete rest — with a choice of Mifflin–St Jeor, Harris–Benedict, or Katch–McArdle.

Estimate your total daily energy expenditure and the calorie intake for losing, maintaining or gaining weight at a chosen rate.

Estimate calories burned during any activity using MET values from the Compendium of Physical Activities.

Estimate blood alcohol content from standard drinks, body weight and time using the Widmark formula — an educational estimate, not a substitute for a breath or blood test.

Estimate glomerular filtration rate (eGFR) from a serum creatinine result, age and sex, using the 2021 CKD-EPI creatinine equation.

Calculate body surface area using the Du Bois, Mosteller, Haycock and Gehan–George formulas used in clinical dosing.

Estimate your one-rep max from a set at any weight, using five published formulas, plus a full percentage training table.

Find your training heart rate zones using the Karvonen method, which accounts for resting heart rate rather than age alone.

Solve for running pace, finish time or distance from whichever two you know, and see predicted finish times for a 5K, 10K, half marathon and marathon at that pace.

Work out daily protein, carbohydrate and fat targets in grams from your calorie needs, a choice of BMR formula, and a chosen macronutrient split.

Find your daily protein target based on body weight and training goal, with the evidence-based range rather than a single number.

Work out your daily carbohydrate target from your calorie needs, plus the fibre and added-sugar guidelines that go with it.

Work out your daily fat target from your calorie needs, along with the saturated fat limit recommended for cardiovascular health.

Estimate how much water to drink a day from body weight, exercise and climate, against the National Academies adequate intake.

Estimate your due date and current gestational age from your last period, conception date, an ultrasound dating scan, or IVF transfer date.

Estimate your ovulation date and fertile window for this cycle and the next two, from your last period and average cycle length.

Predict your next several period dates, with the fertile window and estimated ovulation day for each cycle, from your last period and typical cycle length.

See the recommended weight gain range for your pre-pregnancy BMI, based on Institute of Medicine guidelines, and how it compares to your gain so far.

Find the best bedtime or wake-up time based on 90-minute sleep cycles, or work backward from a target number of hours of sleep.

Estimate a child's likely adult height from both parents' heights, using the mid-parental (target height) method.

Convert between HbA1c and estimated average glucose (eAG) in both mg/dL and mmol/L, using the ADAG study formula.

Classify a blood pressure reading against the 2017 ACC/AHA categories, with the pulse pressure and mean arterial pressure worked out.

Work out what smoking costs per day, year and decade, and what the same money would be worth invested instead.

Estimate VO2 max from the Cooper 12-minute run, a resting and maximum heart rate, or the Rockport walk test, with fitness norms by age and sex.

Convert a dog's age to human years using the 2020 DNA methylation formula and size-banded veterinary charts, instead of the inaccurate times-seven rule.