Fitness & Health

Fat-Free Mass Index (FFMI) Calculator

Calculates your Fat-Free Mass Index and a normalized FFMI from weight, height, and body-fat percentage. It compares your result against the Kouri 1995 natural muscularity range used in sports medicine.

How to use
  1. Enter your weight and height.
  2. Enter your body-fat percentage.
  3. Compare against the natural range shown.
Estimates for general wellness, not medical advice. Check with a doctor or dietitian before acting on health figures.
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Reference ranges

FFMIInterpretation
18-20Average
22-23High, near natural ceiling
25+Rarely reached without drugs

Common questions

What is a good FFMI?

Most fit men land between 18 and 22. Values around 25 mark the upper edge of what's typically reachable naturally per the Kouri 1995 data.

Why normalize FFMI?

Normalizing adjusts FFMI to a standard height of 1.8 m so taller and shorter people can be compared fairly.

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