Lean body mass calculator
Lean body mass covers muscle, bone, water and organs, and is used for some drug doses and protein targets.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter sex, weight and height.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
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 0.3281W + 0.33929H − 29.5336, women 0.29569W + 0.41813H − 43.2933 (W kg, H cm).
Example
Inputs: Sex = Male, Weight = 70 kg, Height = 175 cm. Result: Boer (1984): 56 kg; James (1976): 56.5 kg; Hume (1966): 52.8 kg.
Limits and caveats
- They estimate from weight and height only, so two people of the same size get the same answer whatever their muscle.
- The James equation breaks down at severe obesity.
Questions about this tool
Is lean body mass the same as muscle mass?
No. Lean mass is everything that is not fat, including bone, water and organs, so it is larger than muscle alone.
Which equation should I use?
Boer is the one most used in current medical references; comparing all three gives a sensible range.
Can I get it from my body fat percentage?
Yes. Lean mass = weight × (1 − body fat % ÷ 100).