FFMI Calculator
Fat-free mass index, or FFMI, compares lean mass with height, the way BMI compares weight with height. Strength athletes use it to compare people of different sizes.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Lean mass is your weight minus the fat you carry. FFMI is lean mass in kilograms divided by height in meters, squared.
The height-adjusted figure adds 6.1 for each meter that you are below 1.8 meters, and subtracts it for each meter above. It lets people of different heights be compared more fairly. Both figures depend on the body fat number, which is itself an estimate.
Worked example
At 160 lb, 68 in tall, and 15% body fat, the FFMI is 20.7, and the height-adjusted figure is 21.1.
Questions
Is there a healthy range for FFMI?
This calculator does not give a range or a verdict. Tables for trained people exist, but they differ between sources and are not a health guide.
Why does it need body fat?
FFMI counts lean mass only, so the body fat figure is needed to work out weight minus fat. An estimate still shows trends over time.
Does it work for everyone?
It was developed from studies of strength-trained people, mostly men. It means less for older adults and for people who do not train.
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