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Lean Body Mass Calculator

Calculate your Lean Body Mass (LBM), or your total body weight minus fat mass. Enter a known body-fat percentage, or estimate fat-free mass using the Boer equation.

Enter Your Details

Enter your body fat percentage if known, or leave it blank to use the Boer formula estimate.

kg
cm
%

Leave blank to estimate using the Boer formula.

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What Is Lean Body Mass?

Lean Body Mass (LBM) = Total Body Weight – Fat Mass. It includes:

Muscle

Bone

Organs

Water

LBM can provide additional context for protein planning and TDEE estimates, because lean tissue contributes to resting energy expenditure.

Typical Body Fat % Ranges by Goal

CategoryMen (%)Women (%)
Essential Fat (minimum)2–5%10–13%
Athletic6–13%14–20%
Fitness14–17%21–24%
Average / Acceptable18–24%25–31%
Obese Range25%+32%+

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How the Calculation Works

Asterisks Fit lean body mass calculations utilize standard anthropometric modeling equations:

  • Body-Fat Percentage Method: If your body fat percentage is known, LBM is calculated directly from body weight:Lean Mass = Total Weight × (1 − Body Fat %)This method depends on the accuracy of the body-fat percentage you enter.
  • Boer Equation (1984): If body fat percentage is not provided, the calculator estimates LBM using the Boer mathematical equations:Men: LBM = (0.407 × W) + (0.267 × H) − 19.2 | Women: LBM = (0.252 × W) + (0.473 × H) − 48.3
Formula based on the published equation. Methodology reviewed by the Asterisks editorial team. Last content review: June 2025.
Last Updated: June 2026

Need Help Applying Your Results?

Your estimated lean mass can provide additional context when planning protein intake and resistance training. A coach can help you turn general estimates into a practical routine.

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Frequently Asked Questions

LBM estimates depend on formula assumptions or the accuracy of the body-fat percentage entered. They are not a substitute for clinical body composition analysis. Read disclaimer.