Lean Body Mass Calculator
Calculate your lean body mass from weight and body fat percentage.
See your fat mass, lean mass, and body composition breakdown.
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Lean Body Mass
Lean Body Mass (LBM) is your total body weight minus all fat mass. It includes muscle, bone, organs, and water.
From Body Fat Percentage:
Fat Mass = Weight × (Body Fat % / 100)
Lean Body Mass = Weight - Fat Mass
If body fat % is unknown, use the Boer Formula:
For Males:
LBM (kg) = 0.407 × weight(kg) + 0.267 × height(cm) - 19.2
For Females:
LBM (kg) = 0.252 × weight(kg) + 0.473 × height(cm) - 48.3
Typical body fat ranges:
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Above average | 25%+ | 32%+ |
Why LBM matters:
- Medication dosing: Some drugs are dosed based on lean mass
- Fitness goals: Track muscle gain separate from fat loss
- Metabolic rate: LBM is the primary driver of basal metabolism
- Body composition: A better health indicator than weight alone
Unit conversions:
- 1 kg = 2.205 lbs | 1 lb = 0.4536 kg
- 1 cm = 0.394 in | 1 in = 2.54 cm