FFMI Calculator
Fat-free mass index — muscularity adjusted for height.
Measure it first if you can — every FFMI figure is only as good as this number.
Normalised FFMI
19.7
Average
FFMI interpretation (men; women run roughly 3 points lower)
| Category | FFMI |
|---|---|
| Below average | Below 18 |
| AverageYou | 18 – 20 |
| Fit | 20 – 22 |
| Well trained | 22 – 25 |
| Exceptional | 25 and above |
How the FFMI Calculator works
FFMI does for muscle what BMI does for total weight: it divides fat-free mass by height squared, so a tall person and a short person can be compared fairly. It is the standard way to describe how muscular someone is, and it is far more informative than BMI for anyone who lifts.
Not medical advice. This calculator gives a general estimate, not medical advice. It cannot account for your individual health, medical history, or medication. Talk to a qualified healthcare professional before acting on any result.
Frequently asked questions
How is FFMI calculated?
First find fat-free mass: weight in kg × (1 − body fat ÷ 100). Then FFMI = fat-free mass ÷ (height in metres)². Normalised FFMI adds 6.1 × (1.8 − height in metres), which corrects a bias that otherwise flatters taller people.
What is a good FFMI?
For men, roughly 18 is average, 20 is visibly fit, 22 is well trained and 25 is at the upper edge of what is typically achieved without drugs. For women the same scale sits about 3 points lower. These are descriptive ranges, not goals.
Is an FFMI above 25 proof of steroid use?
No. The figure comes from a 1995 study of bodybuilders which found few drug-free athletes above about 25, and it has been repeated ever since as if it were a hard ceiling. It is a statistical observation from a small sample, not a biological limit, and it depends entirely on the accuracy of the body fat measurement feeding it.
Why is FFMI better than BMI for athletes?
BMI treats all weight the same, so a muscular athlete and someone carrying the same weight as fat get an identical score. FFMI removes fat from the calculation entirely, so what remains actually reflects the tissue that training builds.