FFMI calculator

A worked FFMI example

For a height of 5 ft 10 in, a weight of 180 lb and 15% body fat, the calculation is shown below. Intermediate values are rounded for display.

• Height = 70 in × 2.54 = 177.8 cm = 1.778 m. Height squared = 3.161 m².
• Weight = 180 lb × 0.45359237 = 81.65 kg.
• Fat-free mass = 81.65 × 0.85 = 69.40 kg (153.0 lb).
• FFMI = 69.40 ÷ 3.161 = 21.95.
• Normalized FFMI = 21.95 + 6.3 × (1.80 − 1.778) = 21.95 + 0.14 = 22.09.

What the 1995 study measured

The study included 157 male athletes, 74 who had not used anabolic steroids and 83 who had.

In the group of 74, normalized FFMI reached a clear upper limit of 25.0. Many values in the group of 83 were above 25.0, and some were above 30.

The authors also estimated a mean normalized FFMI of 25.4 for 20 Mr. America winners from 1939 to 1959.

Only men were measured. The authors called their findings preliminary. These values describe the study groups.

FFMI questions

What is FFMI?

FFMI is fat-free mass in kilograms divided by height in metres squared.

How is normalized FFMI calculated?

Normalized FFMI = FFMI + 6.3 × (1.80 − height m). This adjusts the value to the height of a 1.8 m man.

Why does the calculator need body-fat percentage?

Fat-free mass = weight × (1 − body-fat percentage ÷ 100). FFMI uses that fat-free mass, so the result depends on the body-fat percentage entered.

What does the worked example give?

At 5 ft 10 in, 180 lb and 15% body fat, fat-free mass is 69.4 kg (153.0 lb), FFMI is 21.95 and normalized FFMI is 22.09.

Sources

Kouri EM, Pope HG Jr, Katz DL, Oliva P. Fat-free mass index in users and nonusers of anabolic-androgenic steroids. Clinical Journal of Sport Medicine 5(4), 223 to 228, October 1995.

PubMed abstract and study DOI, checked September 30, 2026.