Lean Body Mass Calculator — Boer / Hume formulas
From sex, height and weight, estimate lean body mass, fat mass and body-fat percentage with the Boer or Hume formula.
Input Data
Results
Lean body mass vs fat mass
Boer vs Hume formula estimate
At a glance:Lean body mass (LBM) is weight minus fat: muscle, bone, organs and water. It is a key body-composition metric. This calculator uses the validated Boer (1984) and Hume (1966) prediction formulas needing only height and weight — handy when no specialist equipment is available.
Formula
Boer (1984) male: LBM = 0.407×weight(kg) + 0.267×height(cm) − 19.2.
Boer (1984) female: LBM = 0.252×weight(kg) + 0.473×height(cm) − 48.3.
Hume (1966) male: LBM = 0.3281×weight(kg) + 0.33929×height(cm) − 29.5336.
Hume (1966) female: LBM = 0.29569×weight(kg) + 0.41813×height(cm) − 43.2933.
fat mass = weight − LBM; body-fat % = fat mass ÷ weight × 100%.
$$LBM_{\text{Boer, male}} = 0.407\,W + 0.267\,H - 19.2$$How to Use
- Select sex and enter height (cm) and weight (kg).
- Pick a formula: Boer is common; Hume for comparison.
- The tool shows LBM, lean ratio, fat mass and body-fat %.
- Log results periodically to track fat-loss or muscle-gain progress.
Case Studies
Boer formula (male)
70 kg male, 175 cm: LBM = 0.407×70 + 0.267×175 − 19.2 = 56.0 kg.
Body-fat % ≈ 20%.
Boer formula (female)
55 kg female, 160 cm: LBM = 0.252×55 + 0.473×160 − 48.3 = 41.2 kg.
Body-fat % ≈ 25.1%.
Hume comparison
The same male via Hume gives LBM ≈ 52.8 kg, about 3 kg below Boer.
A normal difference between formulas.
FAQ
Is lean mass the same as muscle?
Not exactly. LBM includes muscle, bone, organs and water; muscle is only part of it (~40–50%). Raising LBM usually means more muscle or bone density.
Which formula is more accurate?
Boer was built on a larger sample and is more common; Hume is older. For typical adults both are within ~±3–4 kg — fine for trend tracking, but not a substitute for DEXA.
Does LBM drop when dieting?
Crash dieting loses muscle too. Keep weight loss ≤1%/week with 1.6–2.2 g protein per kg and resistance training to preserve lean mass.
Why is male LBM higher?
Men naturally have heavier bones and more muscle, so at the same height/weight their LBM is typically 8–15 kg higher than women's.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.