Lean Body Mass (LBM) Calculator

About this calculator

This calculator estimates lean body mass — your total body weight minus body fat, covering muscle, bone, organs and water — from your sex, height and total weight, using the Boer formula, one of the standard equations developed to estimate this figure without specialized scanning equipment. Subtracting the result from total body weight also yields an estimated fat mass.

Lean body mass is a more meaningful number than total weight alone for people tracking fitness progress, since it distinguishes muscle gain from fat loss when weight on the scale barely moves during a training program. It is also used clinically to guide medication dosing and nutritional needs, since some drug dosages and calorie or protein targets are calculated relative to lean mass rather than total body weight, particularly for people with a higher body fat percentage where total-weight-based estimates would be inaccurate.