Lean Body Mass Calculator
BODY COMPOSITION
Lean Body Mass Calculator
Separate estimated fat mass and fat-free mass.
UNDERSTAND YOUR RESULT
How it works
Fat-free mass is everything in body weight other than fat: it includes muscle, bone, water and organs.
THE CALCULATIONFat-free mass = weight × (1 − body fat % ÷ 100)
Using this calculator
Enter your weight and a body-fat percentage from a measurement or estimate. The result splits your weight into fat mass and fat-free mass.
What to keep in mind
This is not a measurement of muscle alone. Any error in the body-fat percentage carries through to the mass estimates.
Frequently asked questions
Are my entries saved?
No. Calculator inputs remain in the current page and are cleared when you reload or leave. The tools do not upload your entries.
Why are results rounded?
The display is rounded for readability. Calculations use unrounded intermediate values. An estimate should not be interpreted as an exact measurement.