Body fat percentage calculator
Estimate body fat percentage from body measurements using the U.S. Navy circumference method.
Enter your values and press Calculate. Your inputs stay in the address, so you can switch language or share the link.
Formula
men: BF% = 495 ÷ (1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450
women: BF% = 495 ÷ (1.29579 − 0.35004×log₁₀(waist+hip−neck) + 0.22100×log₁₀(height)) − 450
How it works
The U.S. Navy method estimates body fat from a log-based formula using neck, waist (and, for women, hip) circumference together with height - no scale or clinical scan is needed, only a tape measure.
Worked example
The same calculation with the default values:
- Sex Male
- Height 175 cm
- Neck circumference 38 cm
- Waist circumference 85 cm
- Hip circumference (female only) 95 cm
- waist minus neck = 85 − 38 = 47 cm
- log₁₀(47) = 1.672098 log₁₀(175) = 2.243038
- denominator = 1.0324 − 0.19077×1.672098 + 0.15456×2.243038 = 1.060098
- BF% = 495 ÷ 1.060098 − 450 = 16.938027%
Result: Estimated body fat: 16.94% · Category: Fitness
This is a circumference-based estimate, not a clinical body-composition measurement (such as DEXA or hydrostatic weighing) - results can differ by several percentage points from more precise methods.
Common mistakes
- Measuring circumferences loosely, inconsistently, or over thick clothing, which skews the result.
- Comparing this estimate directly to a clinical body-composition scan as if they measure exactly the same thing.
- Treating the result as a medical diagnosis rather than a general fitness estimate.
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