FFMI Calculator
FFMI measures how much muscle you carry for your height, independent of fat. Come from the body fat calculator and your numbers are already here.
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Example
A 180 lb (82 kg) man at 15 % body fat and 5 ft 11 in has 70 kg of lean mass, an FFMI of 21.4 and a normalized FFMI of 21.4: above average.
Method and formula
FFMI = lean mass (kg) / height (m)². Normalized FFMI adds 6.1 × (1.8 − height in m) to compare people of different heights (Kouri et al., 1995).
Interpretation for men: under 18 below average, 18 to 20 average, 20 to 22 above average, 22 to 25 excellent, 25+ exceptional. Women run about 3 points lower.
Limits
- FFMI inherits the error of your body fat estimate.
- The famous "25 natural limit" comes from one study of 157 athletes; it is a reference, not a law.
FAQ
What is a good FFMI?
Above 20 for men and 17 for women means a clearly trained physique. 22 to 25 for men is an advanced natural lifter.
Is FFMI better than BMI?
For trained people, yes: it separates muscle from fat instead of lumping them together.
Free educational tool. Body composition, calorie and heart rate values are estimates from published formulas, not medical measurements. They do not replace a professional assessment. No weight-loss recommendation is intended for people under 18.