Lean Body Mass Calculator
Lean body mass (LBM) is your total weight minus fat — muscle, bone, organs, and water. It is a more accurate basis for nutrition planning than total weight.
⚕️ Health Disclaimer: This calculator is for educational purposes only and is not a substitute for professional medical advice.
How It Works
Uses body fat % if known, otherwise uses the Boer formula (height and weight based) to estimate LBM.
Formula
From BF%: LBM = Weight × (1−BF%/100)
Boer (men): 0.407W + 0.267H − 19.2
Boer (women): 0.252W + 0.473H − 48.3
Example
70 kg person, 20% body fat:
LBM = 70 × 0.80 = 56 kg lean mass, 14 kg fat
When to Use This Calculator
Use to calibrate protein intake to lean mass, track muscle gains during body recomposition, or understand composition beyond just weight.
Common Mistakes to Avoid
- Not updating LBM as you progress — recheck every 4–8 weeks.
- Assuming higher LBM is always better — appropriate LBM for height and frame matters.
- Confusing LBM with fat-free mass — they are the same measurement.
Frequently Asked Questions
Typical LBM values?
Men: 60–80 kg. Women: 40–60 kg. Athletes can significantly exceed these ranges.
Gain LBM while losing fat?
Yes — body recomposition is possible, especially for beginners with adequate protein and resistance training.
How accurate is Boer formula?
±4–5% accuracy. DEXA scan is the gold standard but expensive.
Why use LBM for protein?
Fat tissue has minimal protein needs. LBM-based calculation avoids over-recommending protein.
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Last Updated: July 4, 2026