How to estimate your lean body mass
- Choose metric or US units and your Sex.
- Enter your height and weight. If you know your body fat percentage from a scale or scan, add it for a direct figure.
- Read your lean body mass from the Boer formula, with the James and Hume formulas and the body fat each one implies.
The formulas
Weight in kg, height in cm.
| Formula | Men | Women |
|---|---|---|
| Boer (1984) | 0.407 W + 0.267 H − 19.2 | 0.252 W + 0.473 H − 48.3 |
| James (1976) | 1.1 W − 128 (W ÷ H)² | 1.07 W − 148 (W ÷ H)² |
| Hume (1966) | 0.32810 W + 0.33929 H − 29.5336 | 0.29569 W + 0.41813 H − 43.2933 |
Using lean body mass
Lean mass burns more energy than fat, so it is the basis of the Katch-McArdle equation for resting calories, which the BMR calculator uses when you give it your body fat. Tracking lean mass alongside weight also shows whether weight you lose is fat or muscle. The James formula gives odd results at high weights, because its squared term grows quickly, so lean on Boer or Hume in that case.