Lean Body Mass Calculator
Estimate your lean body mass and fat mass from your weight and height.
Sex
kg
cm
23%
fatLean mass
76.8%
Fat mass
23.2%
- 1
Weight term (0.407 × kg)
0.407 × 80 = 32.56 - 2
Height term (0.267 × cm)
0.267 × 180 = 48.06 - 3
Lean body mass (Boer — male)
32.56 + 48.06 − 19.2 = 61.4
Formula
How this is calculated
This calculator takes three inputs: biological sex, body weight in kilograms, and height in centimetres. It applies the Boer formula, a regression equation fitted to body-composition data that uses sex-specific coefficients because men and women carry lean tissue in different proportions. For men, lean body mass equals 0.407 times weight (kg) plus 0.267 times height (cm) minus 19.2; for women it equals 0.252 times weight plus 0.473 times height minus 48.3. The result is your fat-free mass in kilograms — muscle, bone, organs, and water.
Fat mass is then derived by simple subtraction: total weight minus lean body mass. Dividing that fat mass by total weight and multiplying by 100 gives an approximate body fat percentage, shown in the donut chart.
Because Boer is a statistical prediction from height and weight alone, it cannot see your actual muscle-to-fat ratio. It tends to be less accurate for very muscular athletes, the obese, or children, where direct methods like DEXA or hydrostatic weighing are preferable. Treat the output as a trend indicator, not an exact measurement.
Examples
| Input | Result |
|---|---|
| Male, 80 kg, 180 cm | LBM ≈ 61.5 kg |
About this calculator
Lean body mass (LBM), also called fat-free mass, is the weight of everything in your body except fat: muscle, bone, organs, and water. Knowing it is useful for setting protein targets, judging muscle gain or loss, and for clinical drug dosing. The Boer formula estimates LBM from total weight and height with separate coefficients for men and women.
Subtracting lean mass from total body weight gives an approximate fat mass, from which a rough body fat percentage follows. Predictive formulas like Boer are convenient but are estimates; for precise composition, methods such as DEXA scanning, hydrostatic weighing, or bioelectrical impedance are more accurate. Use this result to track trends rather than as an exact figure.
Frequently asked questions
It is your total body weight minus fat — including muscle, bone, organs, and body water. It is also called fat-free mass.
It helps set protein intake, track muscle changes during training or dieting, and is used clinically to dose certain medications.
It is a solid predictive estimate for most adults, but scans like DEXA give more precise composition for athletes or unusual body types.
Also known as
TG we-Calculate Editorial Team. (2026). Lean Body Mass Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/lean-body-mass-calculator
TG we-Calculate Editorial Team. "Lean Body Mass Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/lean-body-mass-calculator.
TG we-Calculate Editorial Team, "Lean Body Mass Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/lean-body-mass-calculator
@misc{wecalculate_lean_body_mass_calculator, title = {Lean Body Mass Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/lean-body-mass-calculator}}, year = {2026}, note = {TG we-Calculate} }
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