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Lean Body Mass Calculator
Calculate fat-free and fat mass from body weight and a known body-fat percentage.
- Fat-free mass, kg
- 56
- Fat mass, kg
- 14
How the calculation works
Fat mass = weight × body fat/100; fat-free mass = weight − fat mass.
Inputs
- Weight, kg
- Measured body fat, %
Calculation details
An adult estimate, not for children, pregnancy, or a personal treatment plan. Discuss results with a clinician or dietitian when managing illness or changing your diet.
Fat-free mass includes water, bone, and organs; it is not muscle mass. Accuracy depends on the original body-fat measurement.
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Updated: 2026-10-02