How accurate is the U.S. Navy body fat method?

It is generally accurate to within a few percentage points for most people when measurements are taken carefully, making it a practical option outside a clinical setting.

Where exactly should I measure my waist?

For this method, measure at the navel for men, and at the narrowest point of the waist for women, keeping the tape level and snug but not compressing the skin.

Why do women need a hip measurement but men do not?

The formula was derived separately for each sex from population data, and the version for women includes hip circumference because it improved accuracy for typical female fat distribution.

Health & Fitness

Body Fat Calculator

Enter your height and a few circumference measurements to estimate your body fat percentage using the widely used U.S. Navy method.

Your calculation is performed in your browser.

Enter your measurements above to estimate your body fat percentage.

This result is an estimate for informational and educational purposes. It isn’t a diagnosis and isn’t a substitute for advice from a doctor, registered dietitian, or other qualified professional. See our methodology and sources for the formula used and its limitations.

How it works

The U.S. Navy method estimates body fat percentage from circumference measurements at the neck and waist (plus hips for women) relative to height, using a logarithmic formula developed and validated for the U.S. Navy fitness program.

Formula & methodology

This uses the U.S. Navy circumference method, which estimates body fat from tape measurements. The equations expect measurements in inches, so centimetre inputs are converted first. The result is limited to a 2–60% range. If you also enter your weight, fat mass and lean mass are worked out from the percentage.

MenBody fat % = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450

WomenBody fat % = 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450

Fat massFat mass = Weight × Body fat % ÷ 100

Lean massLean mass = Weight − Fat mass

What each term means

Waist, neck, hip and height: Measurements in inches.
Logarithm (log₁₀): The base-10 logarithm. It answers “10 to what power gives this number?”
Weight: Optional. Body weight, used only for fat and lean mass.

Body fat categories

Category	Men	Women
Essential fat	Under 5%	Under 13%
Athletes	5 – 13%	13 – 20%
Fitness	13 – 17%	20 – 24%
Average	17 – 24%	24 – 31%
Obese	24% and above	31% and above

Worked example

A man who is 180 cm tall with a 38 cm neck and 93 cm waist has an estimated body fat of about 15%, in the "Fitness" range.

Common uses

—Estimating body fat percentage without access to a DEXA scan or hydrostatic weighing.
—Tracking body composition changes over time alongside weight and BMI.
—Getting a fitness-category estimate for personal training or athletic assessment.

Important notes

—Measure circumferences with a flexible tape at the widest point for the waist and hips, and just below the larynx for the neck, without pulling tight.
—This method gives an estimate, not a clinical measurement — DEXA scans or hydrostatic weighing are more precise but far less accessible.