FFMI Calculator
Calculate your Fat-Free Mass Index using the Kouri et al. framework. See your raw FFMI, normalized FFMI, and how close you are to the common natural ceiling benchmark of 25.
FFMI = fat-free mass (kg) ÷ height² (m) · Normalized FFMI = FFMI + 6.1 × (1.8 − height)
FFMI is a modeling tool, not a diagnosis. Small body-fat measurement errors can shift the result meaningfully.
Clear numbers first, practical next steps after.
Every calculator is built to give you an estimate you can actually use for nutrition, training, or body-composition planning.
Use a DEXA scan, hydrostatic weighing, or a consistent visual guide if you don't have a precise body-fat reading.
How to interpret your FFMI
Raw FFMI tells you how much fat-free mass you carry relative to height. Normalized FFMI adjusts that number to a standard height so the score is more comparable across lifters.
The result is only as accurate as your body-fat estimate. DEXA and hydrostatic testing are better than visual guesses, calipers, or low-cost impedance scales.
Where FFMI fits in your stack
FFMI is strongest when used with lean body mass, body-fat trends, and training performance. It does not replace progress photos or gym logs, but it gives them context.
If your FFMI is rising while body fat stays steady, your training and nutrition are likely moving in the right direction.
Frequently Asked Questions
What is FFMI?
FFMI stands for Fat-Free Mass Index. It adjusts your fat-free mass for height, which makes it more useful than body weight alone when comparing muscularity.
What is a good FFMI score?
Around 18 to 20 is above average, 20 to 22 is excellent, and scores above 25 are uncommon without exceptional genetics or drug use. It is a benchmark, not a hard law.
Why does normalized FFMI matter?
Normalized FFMI adjusts everyone to the same reference height. That makes comparisons fairer between shorter and taller lifters.
Related Calculators
Track the inputs behind your FFMI
Use BodyRecomp to log body fat, body weight, and training progress so your FFMI trend is based on real data instead of one-off snapshots.