Fat mass
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Lean Body Mass Calculator
Calculate how much of your body weight is lean tissue —muscle, bone, and organs —versus fat mass. A key metric for athletes and body composition tracking.
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Lean body mass (Boer formula)
Lean %
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How lean body mass is estimated
Uses the Boer formula — a population-validated LBM regression developed against DEXA scan data. Male: 0.407 × weight(kg) + 0.267 × height(cm) − 19.2. Female: 0.252 × weight(kg) + 0.473 × height(cm) − 48.3. Fat mass = total weight − LBM.
Frequently asked questions
How accurate are the results?
This calculator uses the Boer formula, one of the most accurate LBM estimates validated against DEXA scans. It requires sex, weight, and height — no skinfold measurements needed. Results are population-validated estimates, not medical measurements.
Should I consult a professional?
If you have specific health concerns, existing conditions, or are planning significant lifestyle changes, consult a qualified healthcare provider (doctor, dietitian, physiologist).
How often should I recalculate?
Recalculate when your weight changes more than 5%, activity level shifts significantly, or every 3-6 months for routine monitoring. Results are snapshots — your body changes daily.
About the Lean Body Mass
Free lean body mass calculator using the Boer formula. Enter sex, weight, and height to estimate your lean body mass — muscle, bone, and organs. The tool runs entirely in your browser, so nothing you enter is uploaded or stored.
How to use the Lean Body Mass
- Biological sex — enter your biological sex.
- Body weight (kg) — your body weight in kg.
- Height (cm) — your height in cm.
Last updated
For general wellness information only, not medical advice — see our disclaimer.