The formula

FFMI is your lean mass in kg divided by your height in meters, squared:

fat_free_mass_kg = weight_kg × (1 − bodyFatPercent / 100)
FFMI = fat_free_mass_kg / (height_m)²

The height-adjusted FFMI corrects for lifters who are taller or shorter than the reference height of 1.80 m. This is the version Kouri used to study natural limits:

adjusted_FFMI = FFMI + 6.1 × (1.80 − height_m)

How to read your score

Adjusted FFMI	Interpretation
< 18	Low lean mass — most untrained people sit here
18 – 20	Average lean mass
20 – 22	Above-average, typical of a consistent lifter
22 – 24	Advanced natural lifter, years of consistent training
24 – 25	Elite natural — at or near the natural ceiling
25 – 26	Edge of the natural distribution (Kouri cutoff was ~25)
> 26	Beyond Kouri's upper natural limit; statistically rare without enhancement

About the natural-limit reading

Kouri (1995) lined up the FFMI of tested natural bodybuilders against enhanced ones. He found a natural ceiling near FFMI 25. Later work backs this up and tunes it (Lorente 2021, Helms 2020). The real ceiling sits closer to 25 to 26 for most people. A rare few reach 26 to 27.

A few things to keep in mind. Body-fat methods vary in how far off they can be. A DEXA scan is tight; a tape estimate is loose. A 5% miss on body fat throws your FFMI off by a lot. Read the number as a range, not a fixed point.

FFMI vs. DOTS

DOTS scores how strong you are: how much you lift for your bodyweight. FFMI scores how much muscle you carry for your height. They answer different questions. A strong lifter can have a modest FFMI from wiry strength. A big, muscular person can post a moderate DOTS without meet training.

Track this in Kinoku

The Strength Standards feature scores FFMI next to DOTS and Wilks. It pulls your body-fat number from your profile or Health Connect, and updates on its own as your body changes.