Why we built this
Most fitness apps bury a simple calculation behind a sign-up wall, a subscription, or three screens of ads before you get a number. We thought the formulas themselves — BMI, BMR, body fat, macros — should just be available, instantly, for free, to anyone who wants them.
Every calculator on this site runs entirely in your browser. Nothing you type is saved, uploaded, or shared. Close the tab and it's gone.
How we choose our formulas
We don't invent our own methods. Every calculator on BMI Metrics is built on a formula that's published, peer-reviewed, or in standard clinical use — the Mifflin-St Jeor equation for metabolic rate, the U.S. Navy circumference method for body fat, the Devine formula for reference weight, and the standard WHO definition of BMI. Where a formula has known limits, we say so next to the result rather than hiding it.
Who's behind BMI Metrics
BMI Metrics is maintained by a small team with backgrounds in health content, web development, and data. We're not a hospital, a lab, or a substitute for either — we're writers and developers who care about getting the numbers right and explaining what they mean in plain language.
What we are
An independent, ad-supported publisher of free health and fitness tools and guides.
What we're not
A medical provider, a diagnostic service, or a replacement for professional advice.
How we're funded
Display advertising. We don't sell user data, and we don't require accounts.
Corrections and feedback
If you spot an error in a formula, a broken calculator, or an outdated reference, we want to know. Reach us through the contact page and we'll review it — corrections are usually made within a few days.