Lean Body Mass Calculator
Lean mass and estimated fat from weight, height, and sex.
Inputs
This calculator gives a general estimate and isn't medical advice. It doesn't account for your individual health history — talk to a doctor before making decisions based on it.
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Formula
Male LBM = 0.407×weight + 0.267×height − 19.2 · Female LBM = 0.252×weight + 0.473×height − 48.3
The Boer (1984) formula estimates lean body mass in kilograms from weight and height in centimetres. Subtracting LBM from total weight gives an implied fat mass and body-fat percentage without calipers.
Worked example
A 75 kg man at 175 cm tall carries an estimated 58.9 kg of lean mass and 16.1 kg of fat (~21.5% body fat) — useful for protein targets or comparing against a Navy body-fat measurement.
Where this can give the wrong answer
- Boer assumes average composition; very muscular or very lean athletes may diverge from height-weight regression.
- Implied body fat can disagree with the US Navy circumference method — use one consistent tool when tracking trends.
- Extreme BMI values at the input edges produce estimates that should be interpreted cautiously, not as DEXA replacements.
FAQ
- Lean body mass includes water, bone, organs, and muscle — not muscle alone. It's still a helpful denominator for protein and calorie math when DEXA isn't available.