How to Calculate Lean Body Mass
What is Lean Body Mass?
Lean body mass (LBM) is total body weight minus fat mass. It includes muscle, bone, organs, connective tissue, and water. LBM is used to calculate drug dosages, set protein targets, and assess body composition beyond the limitations of BMI.
Step-by-Step Guide
- 1Boer Formula (most accurate): Men: 0.407W + 0.267H − 19.2; Women: 0.252W + 0.473H − 48.3
- 2James Formula: Men: 1.1W − 128(W/H)²; Women: 1.07W − 148(W/H)²
- 3W = weight in kg, H = height in cm
- 4Fat mass = Total weight − LBM
Worked Examples
Input
Male, 80 kg, 180 cm
Result
LBM ≈ 63–65 kg, Fat ≈ 15–17 kg
~19% body fat
Input
Female, 60 kg, 165 cm
Result
LBM ≈ 45–47 kg, Fat ≈ 13–15 kg
~23% body fat
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