By Coach Jeff Alagar, NASM Physique and Bodybuilding Coach and ISSA Certified Nutritionist. Updated November 2026.
FFMI (fat-free mass index) measures how much lean mass you carry for your height. An average man is around 18 to 20, trained lifters 21 to 23, and about 25 is often cited as the natural upper limit.
How this ffmi calculator works
Lean mass = weight x (1 minus body fat %). FFMI = lean mass divided by height in metres squared. The normalized value adds 6.1 x (1.8 minus your height in m) so lifters of different heights compare fairly. Use the body fat calculator first if you do not know your body fat %.
Frequently asked questions
What FFMI do women usually have?
Average women are about 14 to 17; trained women 17 to 20.
Related calculators
These calculators give general estimates for healthy adults and are not medical advice. If you are pregnant, under 18, or have a medical condition, ask your doctor before changing your diet or training.
