Lean Body Mass Calculator
Estimate how much of your weight is lean tissue: muscle, bone, organs and water.
How to use the Lean Body Mass Calculator
- Choose the sex.
- Choose the units.
- Enter the height – feet.
- Enter the height – inches.
- Enter the height.
- Enter the weight.
- Enter the weight.
- Enter the body fat (optional) – If you know it, lean mass is calculated directly.
- Press Calculate. The result updates automatically as you type, and you can switch the result unit at any time.
About the Lean Body Mass Calculator
Lean body mass is your total weight minus fat. It includes muscle, bone, organs, connective tissue and body water. Doctors use estimates of lean mass to dose some medications and anesthetics, and athletes use it to set protein targets and to see whether weight changes are coming from fat or muscle.
The Boer, James and Hume equations predict lean mass from height and weight alone, so they assume average body composition. They work reasonably for typical adults but underestimate lean mass in muscular people and can be unreliable at very high body weights (the James formula in particular). A measured body fat percentage gives a more personal answer.
Results are estimates for general information only and are not medical advice. Talk to a doctor or registered dietitian before making major changes.
Formula
W = weight in kg, H = height in cm; results in kg.
Boer – men: 0.407W + 0.267H − 19.2; women: 0.252W + 0.473H − 48.3
James – men: 1.1W − 128(W/H)²; women: 1.07W − 148(W/H)²
Hume – men: 0.32810W + 0.33929H − 29.5336; women: 0.29569W + 0.41813H − 43.2933
With a measured body fat percentage: LBM = W × (1 − body fat % ÷ 100).
Example calculation
Using the default values:
- Sex = Male
- Units = US (ft, in, lb)
- Height – feet = 5 ft
- Height – inches = 10 in
- Weight = 170 lb
the calculator returns:
- Lean body mass (Boer): 131.5 lb
- Lean mass share of body weight: 77.4%
- James formula: 133.9 lb
- Hume formula: 123.7 lb
Frequently asked questions
What is a normal lean body mass percentage?
Lean mass is usually around 75–85% of body weight for men and 68–80% for women, the complement of typical body fat ranges.
Is lean body mass the same as muscle mass?
No. Muscle is only part of lean mass; bones, organs, skin and water make up the rest. Skeletal muscle is typically 40–50% of lean mass.
How can I increase lean body mass?
Progressive resistance training combined with adequate protein (around 1.6 g per kg of body weight daily) and enough total calories is the most reliable approach.
Last updated: · Category: Health & Fitness calculators