Lean Body Mass Calculator
Estimate the weight of everything in your body that is not fat — muscles, bones, organs, water — using the Boer and James formulas.
FAQ
Common questions
Why does lean body mass matter?
Lean body mass (LBM) is the single best predictor of resting metabolic rate. Two people of the same weight but different LBM will burn very different amounts of calories at rest.
What's the difference between LBM and FFM?
Strictly speaking, lean body mass includes a small amount of essential fat (around 2–5%), while fat-free mass excludes all fat. In practice, the two terms are used interchangeably.