Lean body mass is everything that isn’t fat: muscle, bone, organs and water. Tracking it tells you whether you’re losing fat or muscle when the scale moves.
How this works
Without a body fat figure, this uses the Boer formula (weight in kg, height in cm):
- Men: 0.407 × weight + 0.267 × height − 19.2
- Women: 0.252 × weight + 0.473 × height − 48.3
If you enter your body fat percentage, lean mass is simply weight × (1 − body fat %), which is usually more accurate.
Results are estimates for general information only and are not medical advice. Talk to your doctor or a registered dietitian before making major changes to your diet or exercise, especially if you are pregnant or have a health condition.
