Your fat-free mass index
The muscle you carry for your height, with the normalisation from the original paper.
Your normalised FFMI
21.6
- Raw FFMI
- 21.5
- Lean mass
- 149.9 lb
- Up to 25
- +23.8 lb of lean mass
The index scaled to 1.80 m, with the coefficient from the paper (6.3). Among Kouri et al.’s 74 steroid-free lifters, it stopped at 25: a benchmark, not proof.
By body fat
Same weight, other body fat levels: the index moves fast.
| Body fat | Raw FFMI | Your normalised FFMI |
|---|---|---|
| 8 % | 23.2 | 23.4 |
| 10 % | 22.7 | 22.9 |
| 12 % | 22.2 | 22.3 |
| 15 % | 21.5 | 21.6 |
| 18 % | 20.7 | 20.8 |
| 20 % | 20.2 | 20.3 |
| 25 % | 18.9 | 19.1 |
Don’t know your body fat?
A tape measure is enough: neck, waist, and hips for women.
- FFMI = lean mass (kg) divided by height (m) squared.
- Normalised FFMI adds 6.3 × (1.80 − height): the coefficient from Kouri et al. (1995), which many calculators copy as 6.1.
- Among their 74 steroid-free lifters, normalised FFMI did not exceed 25.
Frequently asked questions
No. It is the limit seen in a small 1995 sample; some natural athletes exceed it, and estimated body fat has its own error.
The most accurate you have: a 3-point error moves FFMI by almost a point. Our body fat calculator gives an estimate.
The formula applies, but Kouri’s benchmarks come from men: female values are lower.
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