FFMI (fat-free mass index) is how much muscle you carry for your height. It's like BMI but ignores fat, so it measures muscularity instead of weight. The natural limit is about 25 for men: in a 1995 study of 157 male athletes, none of the steroid-free lifters scored above 25.0. Most well-trained natural lifters land between 21 and 23.
These are the bands the BuiltByDe Physique Score uses (normalized FFMI, men).
| FFMI | What it means |
|---|---|
| Under 19 | Below average, or new to lifting |
| 19 - 21 | Average trainee |
| 21 - 23 | Solid - clearly well trained |
| 23 - 25 | High - strong muscular development |
| 25+ | Near or above the natural ceiling |
Example: 180 lb, 5'10" (1.778 m), 15% body fat.
Lean mass = 180 x 0.85 = 153 lb = 69.4 kg
Raw FFMI = 69.4 / (1.778 x 1.778) = 21.95
Normalized = 21.95 + 6.1 x (1.8 - 1.778) = 22.1
An FFMI of 22.1 is solid, well-trained territory. Your FFMI is only as accurate as your body fat number: if you guess body fat too low, FFMI comes out too high. Our body fat guide shows how to estimate it without a scan.
Kouri, Pope, Katz and Oliva measured 157 male athletes, 83 steroid users and 74 non-users. The non-users' normalized FFMI topped out at 25.0, while many users went past 25 and some past 30. Twenty Mr. America winners from the pre-steroid era (1939-1959) averaged an estimated 25.4.
It's a statistical ceiling from one study, not a hard wall: a few genetic outliers go slightly past it. The study included only men, so the 25 figure doesn't directly apply to women, whose natural values run lower. The original paper used a 6.3 height correction; most calculators, including ours, use 6.1, which changes the result by only a fraction of a point.
Source: Kouri EM et al., “Fat-free mass index in users and nonusers of anabolic-androgenic steroids,” Clinical Journal of Sport Medicine, 1995. PubMed
For men, 19-21 is an average trainee, 21-23 is clearly well trained, and 23-25 is high. Most natural lifters with several years of training land around 21-23.
About 25 for men. In a 1995 study of 157 male athletes, no steroid-free lifter had a normalized FFMI above 25.0. It's a statistical ceiling, not a hard wall.
Yes. BMI counts muscle and fat the same, so muscular people often score as overweight. FFMI removes fat from the equation and measures muscle for your height.
Enter your weight, height and body fat in the free Physique Score. It calculates your normalized FFMI and shows where you sit against the natural ceiling.
The Physique Score calculates your FFMI alongside every proportion ratio. Free, no login needed.