Estimate your lean body mass with three formulas.
A man weighing 75 kg and 175 cm tall has an estimated lean body mass of about 57.2 kg using the average of the Boer, James and Hume formulas.
Lean body mass (LBM) is everything in your body except fat: muscle, bone, organs and water. This calculator estimates it with three common formulas — Boer, James and Hume — and shows the body fat each one implies. If you know your body-fat percentage, enter it for a direct figure.
LBM helps set protein targets and drug doses and is the basis of the Katch-McArdle calorie formula in the BMR Calculator. See also the Body Fat Calculator and Protein Calculator.
The calculator applies the standard published formulas step by step.
| Formula | Lean body mass | Implied body fat |
|---|---|---|
| Boer formula | 58.1 kg (128 lb) | 22.6% |
| James formula | 59 kg (130.1 lb) | 21.3% |
| Hume formula | 54.4 kg (120 lb) | 27.4% |
| Weight | Lean body mass |
|---|---|
| 65 kg | 53 kg (116.8 lb) |
| 75 kg | 57.2 kg (126 lb) |
| 85 kg | 61.1 kg (134.6 lb) |
| 95 kg | 64.7 kg (142.6 lb) |
| 75 kg, 20% body fat | 57.2 kg (126 lb) |
Your total weight minus body fat — muscle, bone, organs, skin and water.
They agree within a few kilograms for most people. The Boer and Hume formulas are widely used in medicine; none is a measurement.
LBM includes bones, organs and water as well as muscle, so it is always larger than muscle mass alone.
The James formula assumes lean mass levels off at higher weights, so it can read low in very large bodies.
DEXA scans, hydrostatic weighing and some bioimpedance devices give measured values.
It drives your resting energy use and protein needs and is used to dose some medicines.
It uses the published formula: Boer (men) = 0.407 × W + 0.267 × H − 19.2 LBM = weight × (1 − body fat %) The full method and a worked example are shown on this page.
No. The calculator gives general estimates for information and education. It cannot diagnose or treat anything, so please speak to a doctor or qualified professional about your own health.
Yes. Choose centimetres or feet and inches for height, and kilograms, pounds or stone for weight; the results are converted for you.
No. Everything is calculated in your browser and nothing you enter is uploaded or saved.
