Lean Body Mass Calculator
Calculate your lean body mass and fat mass from weight and body-fat percentage — or estimate LBM from height using the Boer formula.
Lean body mass
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Fat mass —
LBM as % of weight —
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How it works
LBM = weight × (1 − body fat%); Boer: from height and weight by sexFrequently Asked Questions
What is lean body mass?
Everything in your body that isn't fat — muscle, bone, organs and water. At 80 kg with 20% body fat, your lean mass is 64 kg. Tracking it during a diet shows whether you're losing fat or muscle.
Why does lean body mass matter?
It largely determines your metabolic rate and strength potential, and protein and calorie targets are often set per kg of lean mass rather than total weight. Preserving it is the goal of any good fat-loss plan.
How can I estimate LBM without a body-fat measurement?
The Boer formula estimates it from height, weight and sex — useful as a starting point, though a direct body-fat measurement (calipers, DEXA) with the percentage method is more accurate.