LBMCalc is a free tool for estimating lean body mass and related body composition numbers. It exists to give a clear answer quickly, and to show its working so you can judge the result for yourself.
What it does
Enter your sex, height and weight, and the calculator estimates your lean body mass with the Boer, James or Hume equation. If you know your body fat percentage, it can calculate lean mass from that instead. It also reports fat mass, BMI, fat-free mass index (FFMI) and a daily protein range, and shows all three formulas side by side so you can see how much they disagree.
How we keep it honest
- Every equation is published on the home page with its source.
- The calculator warns you when a formula is likely to be unreliable, for example at very high body weight or when the result implies unusually low body fat.
- We describe results as estimates, because that is what they are.
Your privacy
The calculation runs entirely in your browser. The measurements you type are not sent to our server. See the privacy policy for details.
What it is not
This is not a medical device or a substitute for professional advice. If you need an accurate body composition measurement, ask a qualified professional about a DEXA scan or another clinical method.
Get in touch
Found an error, or have a suggestion? Use the contact page.