Bodilab AIFFMI Calculator (Fat-Free Mass Index)
FFMI (Fat-Free Mass Index) measures how much muscle you carry for your height — unlike BMI, it ignores fat. Enter your weight, height and body-fat % below to get your FFMI and adjusted FFMI. For men, ~25 is the commonly cited natural ceiling (Kouri et al., 1995).
Don't know your body fat %? Estimate it from a photo with the free body-fat scanner.
What is a good FFMI?
These are widely-used general reference ranges for the adjusted (height-normalized) FFMI in men. Women typically run a few points lower.
| Adjusted FFMI | Interpretation |
|---|---|
| < 18 | Below average muscle |
| 18 – 20 | Average |
| 20 – 22 | Above average |
| 22 – 23 | Excellent |
| 23 – 25 | Superior (near natural limit) |
| > 25 | Rare naturally — often above the drug-free ceiling |
Reference context: ~25 as an upper limit for natural, trained men comes from Kouri EM, et al., Clin J Sport Med (1995). Ranges are general guidance, not medical cutoffs, and depend on an accurate body-fat estimate.
How is FFMI calculated?
FFMI = fat-free mass ÷ height², where fat-free mass = weight × (1 − body-fat% ÷ 100). The adjusted FFMI adds 6.1 × (1.8 − height[m]) so people of different heights can be compared fairly. This tool shows the adjusted value as the headline number.
Know your FFMI — now track whether it's actually going up.
Bodilab AI estimates your body fat and lean mass from one photo, so you can watch your FFMI move week to week. Figures are estimates, not medical advice.
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What is a good FFMI?
For men, adjusted FFMI ~18–20 is average, 20–22 above average, 22–23 excellent, 23–25 superior. ~25 is the commonly cited natural ceiling (Kouri et al., 1995). Women run a few points lower. General reference, not a medical cutoff.
How is FFMI calculated?
FFMI = fat-free mass ÷ height², with fat-free mass = weight × (1 − body-fat%÷100). Adjusted FFMI adds 6.1 × (1.8 − height[m]) to normalize for height.
Is FFMI better than BMI?
For muscular people, yes — BMI counts muscle like fat. FFMI uses only fat-free mass, so it reflects muscularity. It does need a body-fat estimate.