FFMI Calculator (Fat-Free Mass Index)
Shows how much fat-free mass you carry for your height.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
fat-free mass = weight × (1 − body fat % ÷ 100) FFMI = fat-free mass ÷ height² normalised FFMI = FFMI + 6.3 × (1.8 − height)
Height is in metres. The last step takes a little off for people over 1.8 m and adds a little for people under it, because FFMI tends to rise slightly with height.
What to watch out for
The index and the height correction are from Kouri, Pope, Katz and Oliva (1995), a study of 157 male athletes, 83 of whom used anabolic steroids. Many of the users were above 25, and the non-users in the sample reached about 25.
That is one study of men. It does not set a limit for any individual, and there are no equivalent standards for women.
Frequently Asked Questions
What would 80 kg at 180 cm and 15% body fat read?
21.0. At exactly 1.8 m, the height correction is zero.
What does normalising do?
It adjusts everyone to a height of 1.8 m. At 170 cm and 70 kg with 15% body fat, the raw figure is 20.6 and the normalised one is 21.2.
Why do some sources use 6.1 instead of 6.3?
The abstract of the 1995 paper prints 6.3, while 6.1 circulates widely. The gap is very small: at 1.60 m it is 0.04 points.