Lean body mass calculator
Lean body mass calculator: Boer, James and Hume formulas
Lean body mass (LBM) is your total weight minus the fat in your body: muscle, bone, organs and water. This LBM calculator estimates it from your height, weight and sex with the Boer, James and Hume formulas. They cannot see your real body fat, so treat the numbers as estimates.
Get it on Google Play → Join the iPhone waitlist Available on Android. iPhone coming soon. Free to start.
Use the lean body mass calculator
What is lean body mass?
Lean body mass is everything in your body that is not fat, including muscle, bone, organs, skin and body water. It matters because it burns more energy than fat tissue and affects how medicines are dosed. Strength training and enough protein help keep lean mass, especially while losing weight.
How do I calculate lean body mass?
If you know your body fat percentage, lean mass is your weight times one minus body fat. Without it, formulas estimate it from height and weight. For men, Boer is 0.407 times weight plus 0.267 times height in cm, minus 19.2. Women use different constants.
| Formula | Men | Women |
|---|---|---|
| Boer (1984) | 0.407 x W + 0.267 x H - 19.2 | 0.252 x W + 0.473 x H - 48.3 |
| James (1976) | 1.1 x W - 128 x (W/H)² | 1.07 x W - 148 x (W/H)² |
| Hume (1966) | 0.3281 x W + 0.33929 x H - 29.5336 | 0.29569 x W + 0.41813 x H - 43.2933 |
What is the difference between lean body mass and muscle mass?
Lean body mass includes muscle but also bone, organs and water, so it is always larger than muscle mass alone. A scale that reports muscle mass usually estimates it from body water readings. Neither measure is exact at home, so compare readings from the same device over time.
For a body fat estimate, use the body fat calculator.
Is a lean body mass calculator accurate?
These formulas are averages from groups of people, so your own value can differ by several kilograms, especially if you are very muscular or carry a lot of fat. A DEXA scan or similar test measures it more directly. Use the result to track a trend, not as a precise number.
Log what you eat in the app
A target only helps if you know what you eat. AI Calorie estimates calories and macros from a photo or a short description. It is free to start with daily limits: see pricing. This calculator is not medical advice; see medical review.
Sources
- Boer P. "Estimated lean body mass as an index for normalization of body fluid volumes in humans." Am J Physiol 1984;247(4 Pt 2):F632-F636.
- James WPT. Research on Obesity. London: HMSO; 1976.
- Hume R. "Prediction of lean body mass from height and weight." J Clin Pathol 1966;19(4):389-391.
AI Calorie gives general nutrition information and AI-generated estimates. It is not medical advice. See medical review and our Terms of Use.