FFMI Calculator (Fat-Free Mass Index)
Enter your weight, height and body-fat percentage.
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FFMI Calculator (Fat-Free Mass Index) by TheCalcTools
How the FFMI Calculator (Fat-Free Mass Index) works
FFMI is fat-free mass divided by height squared, like BMI but ignoring fat. Kouri and colleagues (1995) added a height correction, FFMI + 6.1 × (1.8 − height in m), and found few drug-free male athletes above about 25.
Body-fat estimates have errors of several percentage points, which carry into FFMI. Categories are for men; women’s values are typically 2 to 4 points lower.
The formula
Worked example
Using the default values shown in the calculator:
| Weight (kg) | 82 |
|---|---|
| Height (cm) | 178 |
| Body fat | 15 % |
- 82 kg at 15% body fat has 69.7 kg of fat-free mass.
- FFMI 22.00, normalised 22.12: Excellent.
Result:
| FFMI | 22.00 |
|---|---|
| Normalised FFMI (to 1.80 m) | 22.12 |
| Fat-free mass (kg) | 69.7 |
| Category (men) | Excellent |
Frequently asked questions
Is FFMI better than BMI?
For muscular people, yes: it separates muscle from fat. It still depends on an accurate body-fat estimate.
Sources and further reading
- Kouri EM et al. (1995). Fat-free mass index in users and nonusers of anabolic-androgenic steroids. Clin J Sport Med 5:223-228
- Wikipedia: Fat-free mass index
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This calculator gives general estimates for information and education. It is not medical advice and does not diagnose anything. Talk to a qualified health professional about your own situation. See our disclaimer.