Weight, Height, Body fat
FFMI Calculator (Fat-Free Mass Index)
Measure how much lean mass you carry for your height.
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How this calculator works
Fat-free mass index works like BMI but counts only lean mass, so it separates muscular people from people carrying extra fat. The normalized version adjusts the value to a height of 1.80 m so that people of different heights can be compared. In the study that introduced it, natural male athletes rarely exceeded a normalized FFMI of about 25.
Formula
- Fat-free mass = weight × (1 − body fat % / 100)
- FFMI = fat-free mass (kg) / height (m)²
- Normalized FFMI = FFMI + 6.1 × (1.80 − height in m)
Worked example
80 kg, 180 cm, 15% body fat
- Weight
- 80 kg
- Height
- 180 cm
- Body fat
- 15%
ResultFFMI 21.0
Normalized to 1.80 m: 21.0. Fat-free mass is 68.0 kg.
Things to keep in mind
- The result is only as good as the body fat estimate you enter.
- For general information only. It is not medical advice; talk to a health professional about your own situation.
Frequently asked questions
What is a good FFMI?
For men, about 18-20 is average, 20-22 is above average and 22-25 is very muscular. Women typically score 3 to 4 points lower.
What is the natural FFMI limit?
A 1995 study found that male athletes who had not used steroids rarely exceeded a normalized FFMI of 25. It is a statistical observation, not a hard limit.
How is FFMI different from BMI?
BMI uses total weight, so muscle and fat count the same. FFMI removes fat first, so it reflects muscularity.
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Results are estimates based on the values you enter and the published method shown above. They do not replace professional medical, financial or legal advice. Method reviewed October 7, 2026. About this site