Fat-Free Mass Index (FFMI) Calculator

Measure muscularity independent of height.

Weight

Body fat (%)

Height

FFMI 20.988

Adjusted FFMI 20.988

Formula: FFMI = lean mass ÷ height²

Step-by-step with your numbers:

1. Values used:

2. Weight = 80

3. Body fat = 15 %

4. Height = 180

6. FFMI = 20.988

7. Adjusted FFMI = 20.988

Did we solve your problem today?

FFMI gauges muscle mass relative to height — popular in fitness.

The math behind it

Lean mass = weight × (1 − body fat%); FFMI = lean mass ÷ height². Adjusted FFMI normalizes to 1.8 m.

80 kg, 15% fat, 180 cm → FFMI ~21.0.

Natural limit?

An adjusted FFMI around 25 is often cited as a drug-free ceiling.