Lean Body Mass Calculator
Cross-validate your lean mass using Body Fat %, Boer, and James formulas
Enter Details
kg
cm
%
Results
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Enter your details and click Calculate.
Formula
Boer (men): LBM = 0.407·weight + 0.267·height − 19.2 James (men): LBM = 1.1·weight − 128·(weight/height)²
- weight (kg) — Total body weight
- height (cm) — Standing height
Example: Male, 80 kg, 180 cm → Boer LBM ≈ 62.1 kg, James LBM ≈ 62.8 kg
Interpreting Your Result
Higher LBM
Better metabolic health
More lean mass = higher resting metabolic rate
Declining LBM with age
Sarcopenia risk
Resistance training and protein help preserve lean mass
Frequently Asked Questions
What is lean body mass?
LBM is everything except fat — muscles, bones, organs, water. It's the metabolically active part of your body.
Why do Boer and James give different results?
Each was derived from a different population sample. Averaging the two is a reasonable estimate for most people.