FFMI Calculator
Calculate your fat free mass index.
Body metrics
FFMI result
Based on your weight, height, and body fat percentage.
What is FFMI?
The Fat Free Mass Index is a formula that estimates how much lean mass you carry relative to your height.
It is a practical tool for bodybuilders and athletes who want to track muscularity over time.
FFMI score reference
| Men | Women | Description |
|---|---|---|
| 18-20 | 15-17 | Average |
| 20-22 | 17-18 | Good |
| 22-23 | 18-19 | Excellent |
| 23-28 | 19-25 | Superior |
| 28+ | 25+ | Unnatural |
FFMI vs BMI
BMI uses only height and body weight to classify whether someone is underweight, normal weight, overweight, or obese.
FFMI is more useful for athletic populations because it accounts for lean mass instead of treating all weight the same.
Athletic people often show elevated BMI values because of muscle mass, even when they are healthy and lean.
How to calculate FFMI
FFMI is calculated by dividing your lean body mass by the square of your height in meters.
LBM = Body Weight - (Body Weight × Body Fat Percentage)
FFMI = LBM / (Height in meters)^2