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FFMI Fat-Free Mass Index

FFMI Calculator

Work out your fat-free mass index and see how it compares to the natural limit.

Height
ft
in
Weight
lb
Body fat 18%

Average. Flat stomach, little visible definition.

Your FFMI
21.3
Unadjusted
21.2
Lean mass
148lb
Above average 3.7 from the natural ceiling
Natural limit 25
14 30

Clear evidence of consistent resistance training.

What counts as a good FFMI?

FFMI measures how much lean mass you carry for your height, so unlike BMI it is not thrown off by body fat. The scale below follows the research that established roughly 25 as the practical ceiling for men training without drugs. Women are scored on their own lower scale, about three points below the men’s.

FFMI classification, height-adjusted
Classification Men Women
Below average Under 18 Under 14
Average 18 to 20 14 to 16
Above average 20 to 22 16 to 18
Athletic 22 to 23.5 18 to 20
Superior 23.5 to 25 20 to 22
Very high 25 to 28 22 to 24
Exceptional 28 and above 24 and above

The height-adjusted figure adds 6.1 × (1.8 − your height in metres) to the raw number, so a shorter and a taller lifter can be compared fairly. The natural limit of 25 comes from a 1995 study of 157 male athletes, in which no drug-free lifter exceeded it.

Lean mass is what moves this number. Protein intake is the lever that builds it.

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