Lean Body Mass Calculator
Estimate lean body mass and fat mass using the Boer formula.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
This calculator applies the Boer equation to estimate lean body mass from adult sex, weight and height inputs. It is a population equation, not a body-composition measurement; fat mass and body-fat percentage are derived from that estimate and may be inaccurate for an individual.
Worked example
calculated with the default values below
Sex Male · Body weight 80 kg · Height 178 cm Lean body mass 60.9 kg · Fat mass 19.1 kg · Body fat 23.9 %
General background references
Disclaimer
These calculators are for general information only and are not a medical device, a diagnosis or a treatment plan. Reference ranges describe populations, not individuals, and do not account for pregnancy, medication, disability or athletic training. Discuss your own situation with a qualified healthcare professional.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
LBM = {0.407 × W + 0.267 × H − 19.2, s = ♂; 0.252 × W + 0.473 × H − 48.3, s = ♀}; bodyFat = (W − LBM) ÷ W × 100
- W
- body weight (kg)
- H
- height (cm)
- LBM
- lean body mass (kg)
- bodyFat
- body fat percentage
- s
- sex (s = ♂ male, s = ♀ female)
Boer equation for adults; fat mass and body-fat percentage are derived from the estimate. Inputs that produce an estimate outside 0 < LBM < weight are rejected rather than clamped.
Frequently asked questions
Does this measure body fat?
No. It estimates lean body mass with the Boer equation; fat mass and body-fat percentage are derived from that estimate. These are not direct measurements and may differ from an individual’s body composition.