Is FFMI the same as lean body mass?
No. Lean body mass is the amount of fat-free tissue you carry. FFMI indexes that amount against height.
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FFMI Calculator
Calculate fat-free mass index, normalized FFMI, lean mass, and fat mass from height, weight, and body fat percentage.
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How FFMI is calculated
FFMI compares your fat-free mass to your height, so it is more useful than BMI for muscular people.
Normalized FFMI adjusts the score toward a 1.8 m reference height, which makes comparisons between shorter and taller people fairer.
FFMI = fat-free mass (kg) / height (m)^2 Normalized FFMI = FFMI + 6.1 x (1.8 - height in m)
Frequently asked questions
What makes FFMI inaccurate?
The largest error usually comes from the body fat percentage estimate. Use the same body-fat method each time you track it.