About FitCalc

FitCalc is a collection of free, browser-based health and fitness calculators. It covers body composition — BMI, body fat percentage, lean body mass, ideal weight and waist-to-hip ratio — the energy side of nutrition with BMR, TDEE, calorie deficits and macro and protein targets, and the training side with one-rep max, VO2 max and heart-rate zones. Everyday measures such as water intake and step-to-distance conversions are here too.

Every calculation runs locally in your browser. Heights, weights, tape measurements and training numbers you type are never uploaded, stored or transmitted. There is no sign-up, no account and nothing behind a paywall.

The calculators use published, peer-reviewed equations and standards-body methods — Mifflin-St Jeor, Harris-Benedict and Katch-McArdle for metabolic rate, the US Navy and Army circumference equations for body fat, Epley and Brzycki for one-rep max, and the Karvonen method for heart-rate zones. Where an estimate has a known accuracy range we say so, and the accompanying guides explain the arithmetic so you can check the result rather than simply trust it.

Important: FitCalc is for general education only. Results are estimates, not medical advice, diagnosis or treatment, and they cannot account for individual medical conditions. Consult a qualified healthcare professional before changing your diet, exercise or health routine.