FFMI: What Lean Mass Per Height Tells You
BMI cannot tell muscle from fat. FFMI tries to, by starting from lean mass instead of total weight.
What is the FFMI Calculator?
Fat-free mass index (FFMI) looks at lean mass relative to height, which makes it a useful companion to BMI for people who train. Enter your weight, height, and body fat estimate and the tool works out lean mass first, then FFMI. Because body fat estimates vary, treat the result as an estimate, not a precise lab value.
How to use it
- Enter your weight and height.
- Enter your estimated body fat percentage.
- Click Calculate FFMI.
Worked example
80 kg at 180 cm with 15 percent body fat gives 68 kg of lean mass and an FFMI of 20.99.
What is a typical FFMI?
Values in the high teens to low twenties are common for trained adults, but there is no single ideal figure, and the body fat input drives the result.
Frequently asked questions
How accurate is my body fat input?
Home estimates can be off by several percent, so treat FFMI as a ballpark figure.
Can FFMI be too high?
Very high values usually reflect heavy muscle mass, but the figure alone says nothing about health.