Fitness calculators

Understand adult BMI and why it cannot diagnose anorexia, assess an eating disorder or establish an underweight target.

Compare the 2026 Army waist-to-height threshold using recorded measurements, or explore the historical 2023 body-fat equation.

Calculate adult BMI or CDC BMI-for-age percentiles for ages 2 to under 20, with the screening limits of each method explained.

Estimate adult resting energy expenditure using the available equations, and convert food energy between kilocalories and kilojoules.

Estimate body-fat percentage using historical circumference equations or the age- and sex-adjusted BMI study model.

Estimate adult daily maintenance calories from body measurements and activity assumptions, with food-energy unit conversion.

Estimate activity calories using METs, selected Compendium activities or a distance-and-speed approximation, with gross and net energy shown.

Explore the adult BMI-based reference weight interval for a height, including the exclusive upper boundary and screening limitations.

Compare historical adult reference-weight equations or use CDC child BMI-for-age references without setting a personal target weight.

Compare lean-mass estimates from entered body fat, Boer, James, Hume or the pediatric Peters method, with equation-specific limits.

Estimate a one-repetition maximum from a submaximal lift using Epley, Brzycki and supported Lombardi comparisons.

Explore adult BMI screening categories from height and weight, with clear limits on what the result can say about individual health.

Calculate pace, speed, time and distance, review cumulative splits, or project a finish from the average pace so far.

Compare estimated maximum heart rates and target ranges, or use the talk test to check exercise intensity.