We can use the fat-free mass index (FFMI) as a benchmark to measure lean muscle mass. Different from the body mass index of fat calculated by weight, FFMI is more practical in measuring progress and potential.

The formula of FFMI is as follows:

FFMI =[ kg * (100%- body fat percentage)]/m2.

If the height exceeds1.8m, FFMI (after adjustment) = FFMI+6.0 * (m–1.8m).

So what is normal FFMI? Now that we know what FFMI is, let's discuss the range of male FFMI.

16 ~ 18: Muscle strength is very low.

19 ~ 20: Typical American or European male college students.

2 1~23: very muscular.

24~26: the limit that can be achieved without relying on drugs.

Basically, FFMI is not only the best tool to guess how much lean meat you can gain, but also an accurate indicator to see if you take steroids.