All calculators
19 calculators, each built on a published equation with its source cited on the page. Metric and imperial throughout.
Body composition
- BMI calculatorEnter your height and weight to get your body mass index, the WHO category it falls in, and the weight range that corresponds to a healthy BMI at your height.
- Body fat percentage calculatorFour published methods, in descending order of how much they actually measure. The US Navy method needs only a tape measure, which is why it is the default.
- Lean body mass calculatorThree published equations that predict lean mass from height, weight and sex. All three are shown together, because they disagree and the disagreement is informative.
- Army body composition calculatorThe Army no longer uses the tape test. Since 7 July 2026 the only body composition assessment is waist-to-height ratio, and the standard is a ratio below 0.55.
- Body type calculatorEnter your height, weight and wrist measurement to get your frame size and the closest of the three familiar body type labels. Frame size is a measurement; the label is a description, and it predicts less than you have probably been told.
Energy and intake
- BMR calculatorYour basal metabolic rate is the energy your body uses at complete rest. Three equations are shown together because they genuinely disagree, by 100 to 300 kcal for the same person.
- TDEE calculatorYour total daily energy expenditure is your BMR multiplied by an activity level. All five levels are shown, so you can see how much the choice moves the answer.
- Calorie calculatorA daily calorie target based on your energy use and your goal. Deficits are capped at the lesser of a quarter of your maintenance level or 1,000 kcal, and no target falls below 1,500 kcal for men or 1,200 for women.
- Macro calculatorProtein is set per kilogram of body weight, fat as a share of energy, and carbohydrate takes the remainder. No preset drops fat below the lower bound of the published range.
- Protein intake calculatorA daily protein target in grams. The RDA is shown alongside, because it answers a different question from the one most people are asking.
- Water intake calculatorA body-weight-based estimate with adjustments for exercise and climate. The published reference values are shown alongside, because they answer the same question differently.
- Food score calculatorEnter the calories, fat and fibre from a nutrition label to score a serving. The formula counts calories and fat and gives credit for fibre — and knows nothing else about the food.
Training
- One rep max calculatorEnter a weight and the repetitions you managed with it. All five published equations are shown, because they agree at low repetitions and diverge sharply above ten.
- Calories burned calculatorEnergy used during an activity, from its metabolic equivalent. The figure above resting is shown too, because that is the number that actually reflects what the activity added.
- Target heart rate calculatorFive training zones from your heart rate reserve. Karvonen is the default because it accounts for your resting rate, which a flat percentage of maximum does not.
- Running pace calculatorEnter a distance and a finish time to get pace per kilometre and per mile, speed, splits, and what the same pace would give over other distances.
Weight reference
- Ideal weight calculatorThe four equations below all come from clinical pharmacy, where they normalise drug doses. None was designed to tell anyone what to weigh, so the healthy BMI range is shown first.
- Healthy weight range calculatorThe WHO healthy BMI band, converted to a weight range at your height. It is a wide, population-level band rather than a target.