About Health Calculations
The purpose
Health Calculations exists to make the standard health-math questions — daily calorie burn, BMR, BMI, body composition, macros, hydration — quick to answer and easy to act on.
The tools are designed to be intuitive, modern, and fast. Clean forms, live results, visual breakdowns where they help — and free to use on every device.
Behind each one is a peer-reviewed formula, kept current with the latest research where the science has updated. The formula and its primary source are shown on the page, and the typical accuracy range sits alongside the number.
What you get
Peer-reviewed formulas
Mifflin-St Jeor, Henry/Oxford, Katch-McArdle, US Navy, FAO/WHO PAL — all standard equations from peer-reviewed research.
Cited sources
Every calculator page links the primary literature — PubMed, WHO, FAO, or the relevant clinical guideline.
Free to use
No premium tiers. No upsells. No paywalled features.
Honest accuracy ranges
Accuracy ranges shown where appropriate. Notes on study validation when relevant.
Privacy-first
Calculations run in your browser. Nothing is sent to a server. Nothing is stored. Nothing is shared.
Always improving
We update calculations when better research becomes available. New tools added as they're built.
How we maintain accuracy
Every calculator on this site is built from primary literature — the original study or clinical guideline behind the formula. We cross-check the math against the original published equations and clinical practice guides, then publish the methodology on the same page as the result.
When better research emerges, the calculator gets updated. When a formula has known limitations, those limitations are listed in plain view.
Help us improve
Found something off? Have a source we should add? Want a calculator we don't have yet? We'd like to hear about it.
Calculators provide estimates for general guidance. For decisions specific to your situation, a qualified healthcare professional is the right resource.