Lean Body Mass Calculator
Calculate your lean body mass using Boer, James, and Hume formulas. Compare results across methods and understand your body composition.
Lean Body Mass is your total weight minus body fat. For most adults, LBM is 60-90% of total body weight depending on fitness level.
Calculate your exact LBM using three scientific formulas below.
Your Measurements
Why Choose Forge Lean Body Mass Calculator?
Unlike Omni Calculator, Calculator.net and MyFitnessPal, Forge Lean Body Mass Calculator offers a genuinely free, private, and unlimited experience with no strings attached.
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Last updated: January 2026 • Built with care by iForge Apps
How to use this tool
Select your preferred unit system (Imperial or Metric)
Enter your age and select your gender
Input your height
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