What is the US Navy method for body fat calculation?

The US Navy circumference method estimates body fat percentage using simple body measurements — height, neck, waist and hip (for women). It uses a mathematical formula based on these measurements and is reasonably accurate for most people.

How accurate are circumference-based body fat calculations?

Circumference-based methods like the US Navy formula have an estimated error margin of around 3–4 percentage points. Measurement technique and consistency significantly affect accuracy. DEXA scans are more precise but require specialist equipment.

Where should I measure my waist for body fat calculation?

Measure your waist at the narrowest point — usually around the navel level — while breathing normally. Do not hold your breath or pull in your stomach. The neck should be measured just below the Adam's apple.

What is considered a healthy body fat percentage?

For men, 14–24% is generally considered the acceptable range, with 6–13% being the athletic range. For women, 25–31% is acceptable, and 14–20% is athletic. These are reference ranges, not medical targets.

Free Body Fat Percentage Calculator

Estimate your body fat percentage using the US Navy method — no expensive equipment required. All you need is a tape measure and a few body circumference measurements.

Estimate Your Body Fat %

Measure and enter your circumferences to estimate body fat using the US Navy formula.

Measure all circumferences at the widest or narrowest point as described. For height (imperial), enter your total height in inches (e.g. 5'7" = 67 inches).

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About the US Navy Method

Developed by the United States Navy, this method uses body circumferences and height to estimate body fat percentage using logarithmic equations.

For males: Uses neck and waist circumferences.

For females: Uses neck, waist and hip circumferences.

The method was developed from circumference measurements and compared with laboratory body-composition methods in study settings. It provides an estimate, and measurement technique can meaningfully affect the result.

Body Fat Reference Ranges

Males

Essential Fat2–5%

Athletic6–13%

Fitness14–17%

Acceptable18–24%

Obese Range25%+

Females

Essential Fat10–13%

Athletic14–20%

Fitness21–24%

Acceptable25–31%

Obese Range32%+

How the Calculation Works

Asterisks Fit body fat calculations use the U.S. Navy circumference equations and broad educational reference ranges:

Prediction of Percent Body Fat for U.S. Navy Men from Body Circumferences and Height, James A. Hodgdon and Marcie B. Beckett, Naval Health Research Center, 1984: Uses logarithmic equations mapping height, neck, waist (and hips for females) to estimate body density and fat percentage:Men: %BF = 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76 Women: %BF = 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387These equations were reported to have an error margin of approximately 3–4% compared to hydrostatic weighing.
Reference Categories: The displayed body-fat categories are broad educational ranges, not medical diagnoses.
Tracking Use: The Navy Method can be useful for tracking relative changes over time when measurement technique is consistent.

Formula based on the published equation. Methodology reviewed by the Asterisks editorial team. Last content review: June 2025.

Last Updated: June 2026

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Frequently Asked Questions

Medical Disclaimer: Body fat estimates using circumference measurements have a margin of error. They should not be used as a medical assessment. Full disclaimer →