FFMI Calculator

What FFMI measures

FFMI (Fat-Free Mass Index) is like BMI but built from lean mass instead of total weight, and adjusted for height so lifters of different heights can be compared fairly. It's often used as a rough gauge of how muscular someone is relative to their frame.

The normalized version adjusts further for height differences from a 1.8m reference, making comparisons across a wider range of heights more consistent.

A normalized FFMI around 25 is often cited as roughly the upper natural limit for most lifters, though genetics create real individual variation.

Where these numbers come from

The formulas and default values in this calculator are based on:

• Kouri, E.M. et al. (1995), "Fat-Free Mass Index in Users and Nonusers of Anabolic-Androgenic Steroids," Clinical Journal of Sport Medicine — FFMI and normalized FFMI formulas

These are planning estimates for training purposes. Check with a coach, trainer, or physician before starting a new program or maxing out.