Lean Body Mass Calculator

Boer, James and Hume estimates of lean mass. Free, private and instant.

How to use the Lean Body Mass

  1. Pick metric (cm, kg) or imperial (ft, in, lb) units.
  2. Choose sex: Male or Female.
  3. Enter height.
  4. Enter weight.
  5. Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.

About the Lean Body Mass

Lean body mass is everything in your body that is not fat: muscle, bone, organs and water. It is used for fitness tracking and for dosing some medicines. This calculator averages three well-known formulas.

Also known as: LBM calculator, lean mass calculator, fat-free mass calculator, Boer formula calculator.

Worked example

Lean body mass: 53.7 kg (77% of body weight). About 53.7 kg of your 70.0 kg is lean mass (muscle, bone, organs and water). The rest, 16.3 kg, is estimated fat.

Formula and cut-offs

Boer (men): 0.407 W + 0.267 H - 19.2; (women): 0.252 W + 0.473 H - 48.3. James (men): 1.1 W - 128 (W/H)^2; (women): 1.07 W - 148 (W/H)^2. Hume (men): 0.3281 W + 0.33929 H - 29.5336; (women): 0.29569 W + 0.41813 H - 43.2933. W in kg, H in cm.

Frequently asked questions

What is the difference between lean body mass and fat-free mass?

Lean body mass includes a small amount of essential fat, while fat-free mass excludes all fat. In practice the two terms are often used interchangeably.

Can I increase my lean body mass?

Yes. Resistance training with enough protein and calories is the most effective way to build lean mass at any age.

Which lean body mass formula should I use?

The Boer formula is a common default for adults. The James formula can give odd results at high body weight, and Hume is an older alternative. If you know your body fat percentage, weight x (1 - body fat %) is more direct.

What is the lean body mass for a man, 170 cm and 70 kg?

Lean body mass: 53.7 kg (77% of body weight). About 53.7 kg of your 70.0 kg is lean mass (muscle, bone, organs and water). The rest, 16.3 kg, is estimated fat. Enter your own numbers above for a personal result.

Sources and references

Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.

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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.