Fitness Calculators is a small, focused tool site: a handful of fitness calculators that are fast, free, and honest about how they work.
What Makes This Site Different
- Formulas in the open: every calculator page shows the equation it uses and a worked example, so you can verify the result yourself.
- Private by design: all calculations run in your browser. The numbers you enter are never stored, sent to a server, or shared.
- No sign-up, no paywall: every tool is fully free.
Which Formulas We Use
- TDEE and BMR — the Mifflin-St Jeor equation
- One Rep Max — the Epley and Brzycki formulas, averaged
- BMI — the standard World Health Organization definition and categories
- Body Fat — the US Navy circumference method
- Ideal Weight — the Devine, Robinson and Miller formulas
- Protein targets — evidence-based grams-per-kilogram ranges by goal
- Water Intake — 35 ml per kg body weight plus exercise adjustments
Calculator results are estimates for planning and education. They are not medical advice — please read our Disclaimer.
Who Runs This Site
Fitness Calculators is run by the team behind Precision Strength, a fitness education project that publishes daily exercise-form content. We built these calculators because the ones we found online either hid their formulas, forced a sign-up, or sent the numbers you typed to a server. Ours do none of that.
How to Contact Us
The fastest way to reach us is through our Contact page, which links to our Facebook Page — send a message there mentioning this website and we will get back to you. We read every message, and calculator bug reports are fixed first.