Body Fat Percentage Calculator

Body Fat Percentage Calculator

What this calculator does

Body weight and BMI don't tell you what your body is actually made of - two people at the same height and weight can have very different amounts of muscle versus fat. This calculator uses the U.S. Navy circumference method, a tape-measure-only technique developed for military fitness assessments, to estimate your body fat percentage from a handful of simple measurements. It then places your result into one of five widely used fitness categories, from essential fat through obese.

Formula used

All measurements are converted to centimeters first. The formula differs slightly by gender because fat distribution patterns differ between men and women.

For men:

$$BodyFat\% = \frac{495}{1.0324 - 0.19077 \times \log_{10}(waist - neck) + 0.15456 \times \log_{10}(height)} - 450$$

For women:

$$BodyFat\% = \frac{495}{1.29579 - 0.35004 \times \log_{10}(waist + hip - neck) + 0.22100 \times \log_{10}(height)} - 450$$

Where waist, neck, hip, and height are circumference/height measurements in centimeters. Women additionally require a hip measurement because the formula accounts for a different pattern of fat storage.

How to use it

1. Select your gender - the formula and result categories differ between men and women.
2. Choose whether you're entering measurements in centimeters or inches.
3. Enter your height.
4. Enter your neck circumference, measured at its narrowest point (just below the larynx).
5. Enter your waist circumference - at the navel for men, at the narrowest point of the torso for women.
6. If you selected female, enter your hip circumference at its widest point. This field is ignored for men.
7. Submit to see your estimated body fat percentage, which category it falls into, and the full breakdown of every category's range.

Fitness categories

Men:

Category	Body Fat %
Essential Fat	2% – 5%
Athletes	6% – 13%
Fitness	14% – 17%
Average	18% – 24%
Obese	25%+

Women:

Category	Body Fat %
Essential Fat	10% – 13%
Athletes	14% – 20%
Fitness	21% – 24%
Average	25% – 31%
Obese	32%+

These categories are the widely referenced American Council on Exercise (ACE) ranges - a general guide, not a medical diagnosis. The Navy method itself is an estimate with a typical margin of error of a few percentage points compared to lab methods like DEXA scans.

Example

A male, 178 cm tall, with a 38 cm neck and an 85 cm waist:

$$BodyFat\% = \frac{495}{1.0324 - 0.19077 \times \log_{10}(85 - 38) + 0.15456 \times \log_{10}(178)} - 450 \approx 16.4\%$$

That places him in the Fitness category.