Body composition calculator
FFMI calculator
Fat-Free Mass Index — BMI's muscle-aware cousin. Enter your weight, height, and body-fat % to see how much muscle you carry. Free, instant, no sign-up.
Want to push your FFMI up? The coach builds the training and nutrition to add lean mass.
What is FFMI?
Fat-Free Mass Index is BMI's muscle-aware cousin. Instead of dividing total weight by height squared, it divides your lean mass — so it actually tracks how much muscle you carry for your frame, which is what most lifters care about.
How this calculator works
First we get fat-free mass: weight × (1 − body-fat%). Then FFMI = fat-free mass ÷ height in metres squared. The normalized version adds an adjustment, 6.1 × (1.8 − height_m), so taller and shorter lifters can be compared on the same scale.
FFMI chart for men and women
The same FFMI formula works for men and women; the interpretation changes because average lean mass differs. Treat any FFMI chart as a broad reference, not a verdict. The useful comparison is usually your own normalized FFMI over time, measured with the same body-fat method each time.
Reading your number
Roughly: 18–20 is average, 20–23 is clearly athletic, and the drug-free ceiling sits around 24–25. It depends on an accurate body-fat figure, so treat the result as a ballpark. Want to move it up? The coach builds the training and nutrition to add lean mass over time.