Lean Body Mass Calculator
Estimate your lean body mass and fat mass from your weight and height using the Boer formula.
Enter your details below.
How to use
- Enter your weight in kilograms and height in centimetres.
- Select Male or Female.
- Read your lean body mass and estimated fat mass.
About this tool
Lean body mass is everything that is not fat: muscle, bone, water, and organs. The Boer formula estimates it from weight and height with different coefficients for men and women, and subtracting it from total weight gives an estimate of fat mass. The result is general information only, not medical advice, and like all height-weight formulas it is an approximation, not a measurement.
Frequently asked questions
Why track lean mass instead of just weight?
Two people can weigh the same while one carries far more muscle; lean mass shows whether weight change is coming from muscle or fat.
Does gaining muscle raise lean mass?
Yes — strength training plus enough protein typically raises lean mass, which is why the scale alone can mislead during training.