Lean Body Mass Calculator
Lean body mass (LBM) is your total body weight minus fat mass — muscle, bone, organs, and water — and is a common target for setting protein intake and tracking body-composition change during training. This calculator uses the Boer formula, a validated estimate needing only sex, height, and weight, and also derives your fat mass and body fat percentage from the result. It is an estimate, not a substitute for DEXA or other direct body-composition scans.
Educational estimate only. Results are not medical, legal, or financial advice. Confirm important decisions with a qualified professional.
How it works
- Choose your sex and enter height and weight.
- The Boer formula estimates your lean body mass.
- Read LBM alongside derived fat mass and body fat percentage.
Formula Men: LBM = 0.407×kg + 0.267×cm − 19.2; Women: LBM = 0.252×kg + 0.473×cm − 48.3
Frequently asked questions
What is lean body mass?
It is your total body weight minus fat mass — everything else, including muscle, bone, organs, and body water.
What is the Boer formula?
A 1984 regression formula for estimating lean body mass from sex, height, and weight alone, without needing skinfold or circumference measurements.
How is body fat % derived here?
Fat mass is your weight minus the estimated lean body mass; body fat % is that fat mass divided by your total weight.
Why use LBM for protein targets?
Protein needs scale more closely with lean tissue than with total body weight, so many nutrition guidelines set protein intake per kilogram of lean body mass.
Is this as accurate as a DEXA scan?
No. This is a formula-based estimate from just height and weight. A DEXA scan or other direct body-composition test is more precise if you need clinical accuracy.