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Lean Body Mass Calculator Guide
Estimate your lean body mass (LBM) — the weight of everything in your body except fat, including muscle, bone, organs, and water. It's a useful reference for tracking body composition over time.
Men: LBM = 0.407×weight(kg) + 0.267×height(cm) − 19.2. Women: LBM = 0.252×weight(kg) + 0.473×height(cm) − 48.3.
What Is Lean Body Mass?
LBM is your total weight minus your fat weight. For example, an 80 kg man at 180 cm has an estimated lean body mass of about 61.4 kg, meaning roughly 18.6 kg is fat mass.
Why Track Lean Body Mass?
When losing weight, keeping lean mass while reducing fat is usually the goal. Tracking LBM alongside total weight shows whether changes come from fat or muscle. Formulas like Boer are estimates; methods such as DEXA scans measure body composition directly.
This is a general estimate for information only, not medical or nutritional advice. Individual needs vary with health, goals, and other factors — talk to a doctor or registered dietitian for guidance specific to you.
Related: Body Fat Calculator, BMR Calculator, and One Rep Max.
Frequently Asked Questions
What is lean body mass?
It's your total body weight minus fat weight — muscle, bone, organs, and water combined.
How is lean body mass calculated?
This calculator uses the Boer formula, based on your weight, height, and sex.
Why is lean body mass useful?
It helps you see whether weight changes come from fat or lean tissue, which matters for health and fitness.
How accurate is the estimate?
Formula estimates are approximate; a DEXA scan or similar test measures body composition more precisely.
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