FFMI calculator
The fat-free mass index shows how much lean mass you carry for your height. Unlike BMI, it separates muscle from fat, which makes it a better measure of how muscular someone is.
From the body fat calculator, a smart scale or a DEXA scan.
Normalized FFMI
20.8
Above average
FFMI
20.7
Lean mass
65.6 kg
How FFMI is calculated
Lean mass = weight × (1 − body fat). FFMI = lean mass in kg ÷ (height in m)².
Taller people carry proportionally more lean mass, so Kouri et al. (1995) proposed a normalized FFMI that adjusts every result to a height of 1.8 m: normalized FFMI = FFMI + 6.1 × (1.8 − height in m).
What is a good FFMI?
For men, a normalized FFMI of 18 to 20 is average, 20 to 22 above average, 22 to 23 excellent and above 23 superior. Women typically score about 3 points lower.
In Kouri's study of athletes, men who did not use steroids rarely exceeded about 25. Values above that are uncommon without performance-enhancing drugs, although a few people exceed it naturally.
Limitations
FFMI is only as accurate as the body fat estimate behind it: an error of 3 percentage points in body fat changes FFMI by about 0.75 for an 80 kg man.
Lean mass includes organs, bone and water, not just muscle, so FFMI also runs somewhat higher in people with a lot of body fat.
Sources
- Kouri EM, Pope HG, Katz DL, Oliva P (1995). Fat-free mass index in users and nonusers of anabolic-androgenic steroids. Clinical Journal of Sport Medicine 5(4):223–228.
- Schutz Y, Kyle UU, Pichard C (2002). Fat-free mass index and fat mass index percentiles in Caucasians aged 18–98 y. International Journal of Obesity 26:953–960.