FFMI Calculator
Calculate your Fat-Free Mass Index (FFMI) — a measure of muscularity adjusted for height. Useful for assessing natural muscle-building potential.
FFMI (Fat-Free Mass Index) measures the amount of muscle mass relative to height. It is widely used by bodybuilders to compare muscularity and serves as an alternative to BMI that accounts for body composition.
What is FFMI?
FFMI stands for Fat-Free Mass Index — a measure of the amount of muscle mass relative to height. It is used by bodybuilders to compare themselves to others and serves as an alternative to Body Mass Index (BMI) that better reflects body composition rather than total weight alone.
FFMI Formula
Total Body Fat = Weight × (Body Fat% / 100)
Lean Weight = Weight × (1 − Body Fat% / 100)
FFMI = Lean Weight (kg) / Height (m)²
Adjusted FFMI = FFMI + (6.3 × (1.8 − Height (m)))
The adjusted (normalized) FFMI corrects for height, making it easier to compare people of different statures. It is normalized to a height of 1.8 m (approximately 5'11").
FFMI Interpretation
The table below provides an interpretation of FFMI scores. Note that the ranges for men and women differ because of natural physiological differences in muscle mass distribution. Switch the gender toggle above to see the relevant reference table.
How to Use This Calculator
- Choose your measurement system (imperial or metric).
- Enter your height.
- Enter your weight.
- Enter your body fat percentage.
- Click the Calculate button to get your results.