FFMI Calculator

Q: Do I need my body fat percentage for FFMI?

Yes, body fat percentage is used to separate lean mass from fat mass before calculating the index.

Calculate your Fat-Free Mass Index (FFMI) — a measure of muscularity relative to height, adjusted for natural benchmarks.

Gender

Height (cm)

Weight (kg)

Body Fat % Use our Body Fat Calculator if you don't know this

Normalized FFMI

Lean Body Mass

Fat-free weight used in the calculation.

Raw FFMI

Before the height-normalization adjustment.

How FFMI Is Calculated

FFMI (Fat-Free Mass Index) measures muscle mass relative to height. It's calculated as lean body mass divided by height squared, then normalized to a 1.8m reference height so results are comparable across different heights.

FFMI Benchmarks (Men, Natural Lifters)

FFMI	Interpretation
Below 18	Below average
18–20	Average
20–22	Above average / muscular
22–23	Very muscular
23–25	Exceptional (near natural limit)
25+	Rare without performance-enhancing drugs

Frequently Asked Questions

What is a good FFMI?

For men, a normalized FFMI of 20–22 is considered good, and above 25 is rare without performance-enhancing drugs.

What does FFMI measure?

FFMI measures muscle mass relative to height, giving a sense of how muscular someone is independent of total body weight.

Do I need my body fat percentage for FFMI?

Yes — body fat percentage is used to separate lean mass from fat mass before calculating the index.

Last Updated: July 2026