FFMI (Fat Free Mass Index) measures lean body mass relative to height squared, like BMI but for muscle FFM (kg) / [height (m)]². It doesn't adjust for height variations, so taller people may score lower despite similar muscularity.

Normalized FFMI refines this by scaling to an average height of 1.8m Normalized FFMI = FFMI + 6.1 × (1.8 height in m). This ensures fairer comparisons across heights.

For average height, they're identical otherwise, it boosts scores for taller folks or reduces for shorter ones.

[FFMI calculator](https://macrocodex.app/tools/bmi-ffmi-calculator

It will tell you both normalized and raw FFMI.