FFMI Calculator
FFMI calculator for fat-free mass index: weight, height and body fat give fat-free mass, FFMI and the height-normalized FFMI of Kouri et al. (1995), unrated. How it works
Use the FFMI Calculator
About the FFMI Calculator
FFMI is fat-free mass in kilograms divided by height in meters squared. At 180 lb, 180 cm and 15% body fat, fat-free mass is 69.4 kg and FFMI is 21.4. This FFMI calculator also gives the height-normalized value, FFMI + 6.3 × (1.8 − height in m), from Kouri and colleagues’ 1995 study of 157 male athletes, and it assigns no category.
Normalized FFMI by weight and body fat at a height of 180 cm (70.87 in)
| Weight | 8% body fat | 10% | 12% | 15% | 18% | 20% | 25% |
|---|---|---|---|---|---|---|---|
| 140 lb | 18.0 | 17.6 | 17.2 | 16.7 | 16.1 | 15.7 | 14.7 |
| 150 lb | 19.3 | 18.9 | 18.5 | 17.8 | 17.2 | 16.8 | 15.7 |
| 160 lb | 20.6 | 20.2 | 19.7 | 19.0 | 18.4 | 17.9 | 16.8 |
| 170 lb | 21.9 | 21.4 | 20.9 | 20.2 | 19.5 | 19.0 | 17.8 |
| 180 lb | 23.2 | 22.7 | 22.2 | 21.4 | 20.7 | 20.2 | 18.9 |
| 190 lb | 24.5 | 23.9 | 23.4 | 22.6 | 21.8 | 21.3 | 19.9 |
| 200 lb | 25.8 | 25.2 | 24.6 | 23.8 | 23.0 | 22.4 | 21.0 |
| 210 lb | 27.0 | 26.5 | 25.9 | 25.0 | 24.1 | 23.5 | 22.0 |
| 220 lb | 28.3 | 27.7 | 27.1 | 26.2 | 25.3 | 24.6 | 23.1 |
At exactly 180 cm the height correction is zero, so plain and normalized FFMI are the same number.
How height changes FFMI at 180 lb and 15% body fat
| Height | FFMI | Normalized FFMI |
|---|---|---|
| 160 cm | 27.1 | 28.4 |
| 165 cm | 25.5 | 26.4 |
| 170 cm | 24.0 | 24.6 |
| 175 cm | 22.7 | 23.0 |
| 180 cm | 21.4 | 21.4 |
| 185 cm | 20.3 | 20.0 |
| 190 cm | 19.2 | 18.6 |
| 195 cm | 18.3 | 17.3 |
| 200 cm | 17.3 | 16.1 |
Fat-free mass is 69.4 kg in every row. Below 180 cm the correction adds to FFMI and above it the correction subtracts.
Reference points from Kouri et al. (1995): men, normalized FFMI
| Group in the study | Men | Normalized FFMI |
|---|---|---|
| Athletes who had not used steroids | 74 | up to 25.0 |
| Mr. America winners, 1939 to 1959 (presteroid era) | 20 | estimated mean 25.4 |
| Athletes who had used steroids | 83 | many above 25.0, some above 30 |
The only published figures the page uses. They describe groups of male athletes, not bands for one person, and the study has no women, so the page gives no figures for women. The authors called the findings preliminary.
Methodology
Fat-free mass = weight × (1 − body fat % ÷ 100). FFMI = fat-free mass in kg ÷ (height in m)². Normalized FFMI = FFMI + 6.3 × (1.8 − height in m), the correction given by Kouri et al. (1995). Weight can be entered in pounds or kilograms and height in centimeters or inches. Accepted values are 30 to 300 kg, 100 to 250 cm and 3 to 50% body fat.
Frequently asked questions
- What is the FFMI formula?
- FFMI = fat-free mass in kilograms ÷ height in meters squared, where fat-free mass is body weight × (1 − body fat ÷ 100). A person of 80 kg at 12% body fat has 70.4 kg of fat-free mass, and at 175 cm that is an FFMI of 23.0.
- Is an FFMI of 25 the natural limit?
- That figure comes from one study. Kouri and colleagues found that normalized FFMI among 74 athletes who had not used steroids extended up to 25.0, while many of the 83 steroid users exceeded 25 and some exceeded 30. The same paper estimated a mean of 25.4 for 20 Mr. America winners from 1939 to 1959, and it called its own findings preliminary. It describes a group of male athletes; it is not a test that can be applied to one person.
- What is a good FFMI?
- This page gives the number without a rating. The only reference data behind it are the 157 male athletes of the 1995 study, so there is no reference for women and the page has no sex setting.
- How much does a wrong body fat percentage change FFMI?
- At 180 lb and 180 cm, 14% body fat gives 21.7, 15% gives 21.4 and 16% gives 21.2: about 0.25 per percentage point. FFMI is only as good as the body fat figure you enter, and the page shows this sensitivity for your own numbers.
- Why is FFMI normalized for height?
- Kouri and colleagues added 6.3 × (1.80 − height in m) to bring every result to the height of a 1.8 m man. At 180 lb and 15% body fat, a height of 170 cm gives 24.0 plain and 24.6 normalized, and 190 cm gives 19.2 plain and 18.6 normalized. Many websites quote 6.1 for the correction; the paper’s abstract says 6.3.
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