Lean Body Mass Calculator
Estimate lean mass from total weight and body fat percentage.
Use the calculator below, then review the formula, a numeric example, and the reference table to understand how the lean body mass calculator result is produced.
Educational tool only. It does not replace advice from a licensed clinician, dietitian, or exercise physiologist.
Calculator inputs
Result
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What is this calculator?
Estimate lean mass from total weight and body fat percentage. The formula, a worked example, and a reference table are below. Results are for education only, not medical advice.
How it works
Lean body mass (kg) ≈ weight (kg) × (1 − body fat fraction). Body fat fraction = body fat % ÷ 100.
Example
80 kg at 18% fat → LBM ≈ 80 × (1 − 0.18) ≈ 65.6 kg.
Reference Table
| Value | Meaning |
|---|---|
| Body fat % | Inherits measurement error |
| Hydration | Shifts scale weight |
| Athletes | May carry more lean mass |
FAQ
Is LBM exactly muscle?
No—bone, organs, and water contribute.
Protein targets?
Many coaches anchor protein to lean mass estimates.
DEXA preferred?
For research-grade composition when available.
Cutting phase?
Protect strength training and protein when dieting.