Your Details
kg
cm
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If left blank, formulas will estimate LBM from height and weightBody Composition Results
Lean Mass
0 kg
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Fat Mass
0 kg
0%
Total Weight
0 kg
Lean Mass
0 kg
Fat Mass
0 kg
BMR (Katch-McArdle)
0 kcal
3 Formulas Compared
💡 If you know your body fat %, the direct calculation is always most accurate. The formulas above estimate LBM from height and weight when BF% is unknown.
Why Lean Body Mass Matters
What Is Lean Body Mass?
Also searched as: lean body mass calculator free | lbm calculator | muscle mass calculator | lean muscle calculator
Lean Body Mass (LBM) is the weight of everything in your body except fat — muscles, bones, organs, skin, blood, and water. It's sometimes called Fat-Free Mass (FFM), though technically LBM includes a small amount of essential fat (~2–3%). LBM is the metabolically active portion of your body and directly determines your basal metabolic rate.
How to Use Your LBM
LBM is used to calculate drug dosages, protein targets, and BMR more accurately than total body weight. The Katch-McArdle BMR formula uses LBM directly, making it the most accurate BMR calculation for athletes and lean individuals. For protein targets, using LBM (rather than total weight) prevents overestimating needs in people with higher body fat.
Use the Lean Body Mass Calculator above — enter your values and get instant results. This free online tool calculates how to calculate lean body mass without any download or signup required. Results update in real time as you type.
Use the Lean Body Mass Calculator above — enter your values and get instant results. This free online tool calculates lean body mass vs body fat without any download or signup required. Results update in real time as you type.
Lean body mass includes ALL non-fat tissue: skeletal muscle, organ tissue, bone, blood, water, and connective tissue. Skeletal muscle specifically accounts for roughly 40–50% of LBM in most people. If your LBM is 60 kg, you have roughly 24–30 kg of skeletal muscle.
Yes. Rapid weight loss without adequate protein and resistance training leads to significant LBM loss. Slower weight loss (0.5–1% body weight per week) with high protein intake (2.4–3.1g/kg LBM) and resistance training can preserve and even increase LBM while losing fat — this is body recomposition.