Free online lean body mass calculator
Lean body mass is total body weight minus fat mass. This calculator uses three validated clinical formulas to estimate LBM from weight and height.
Example: 5′10″ = 70 inches
How to use
- Select your biological sex.
- Enter your weight in pounds and height in inches.
- Optionally enter your body fat percentage for a direct LBM calculation.
- Click Calculate LBM.
- See results from three formulas compared side by side.
Formulas
Boer (1984) — default:
- Male: LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2
- Female: LBM = 0.252 × weight(kg) + 0.473 × height(cm) − 48.3
James (1976):
- Male: LBM = 1.1 × weight(kg) − 128 × (weight/height)²
- Female: LBM = 1.07 × weight(kg) − 148 × (weight/height)²
Hume (1966):
- Male: LBM = 0.3281 × weight(kg) + 0.3393 × height(cm) − 29.53
- Female: LBM = 0.2957 × weight(kg) + 0.4181 × height(cm) − 43.29
From body fat %:
- LBM = Total weight × (1 − body fat% / 100)
Worked example
170 lb (77.1 kg) male, 5′10″ (177.8 cm):
Boer LBM = 0.407 × 77.1 + 0.267 × 177.8 − 19.2 = 31.4 + 47.5 − 19.2 ≈ 59.7 kg (131.6 lbs)
Frequently asked
What is lean body mass?
Lean body mass (LBM) is everything in your body that isn't fat — muscle, bone, water, organs, and connective tissue. It is the metabolically active portion of body mass.
Which formula is most accurate?
The Boer formula (1984) is generally considered the most accurate for clinical use. The three formulas give similar results for people of average build, but differ more at extreme heights and weights.
How is LBM different from muscle mass?
Lean body mass includes all non-fat tissue — muscle, bone, organs, and water. Muscle mass is just one component of LBM. They are not interchangeable terms.
What is a healthy LBM?
There is no universal healthy LBM, as it depends on total body weight, height, sex, and goals. Athletes typically have higher LBM relative to body weight. LBM is useful for tracking changes over time.
Why does sex affect LBM?
Males generally have more muscle mass and denser bones than females at the same height and weight, resulting in higher LBM. The formulas use sex-specific coefficients to account for this.