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

The U.S. Navy body fat formula is accurate to within ±3–4% of DEXA scan results for most people. It uses circumference measurements of the neck, waist, and hips (for women) along with height. It is most reliable for people in the normal to moderately overweight range and is one of the most widely validated field methods.

What measurements do I need for this body fat calculator?

You need your height, neck circumference (measured just below the larynx), and waist circumference (measured at the narrowest point, typically at the navel). Women also need a hip circumference measurement at the widest point. You can use either imperial (inches) or metric (centimeters) units.

What is a healthy body fat percentage?

Healthy body fat ranges vary by sex. For men: athletes 6–13%, fitness 14–17%, average 18–24%. For women: athletes 14–20%, fitness 21–24%, average 25–31%. Essential body fat — the minimum needed for organ function — is 2–5% for men and 10–13% for women.

How is body fat percentage different from BMI?

BMI uses only height and weight, so it cannot distinguish between muscle and fat. A muscular person can have a high BMI but low body fat. Body fat percentage directly estimates the proportion of your body that is fat tissue, making it a much more useful metric for people who strength-train.

Free Tool

Body Fat % Calculator

Estimate your body fat percentage using the U.S. Navy method. Enter a few measurements — get your result instantly.

Height

Neck circumference inches

Waist circumference inches — at navel

Hip circumference inches — widest point

Weight (optional — for lean mass estimate)

—

% body fat

—

5% 15% 25% 35% 45%

Body Fat % Categories

Where does your result fall? Here's what each range typically looks like.

2–5

Essential Fat

Minimum for physiological function. Competition bodybuilders on stage. Not sustainable.

6–13

Athletic

Visible abs and muscle separation. Typical of competitive athletes and dedicated lifters.

14–17

Fitness

Lean and toned. Some ab definition, clear muscle shape. Healthy and sustainable.

18–24

Average

Typical range for most men. Soft midsection, limited muscle definition. Healthy range.

25+

Above Average

Excess body fat, visible around waist and chest. Increased health risk at higher ends.

Want a More Accurate Estimate?

Tape measurements give you a rough number. GainFrame uses AI to analyze your actual physique from a photo — no measuring tape needed.

AI-powered body composition analysis
Track body fat % changes over time
See muscle group development visually
Just take a photo — results in seconds

About This Calculator

This calculator uses the U.S. Navy body fat formula, which estimates body fat percentage from circumference measurements. It's widely used and reasonably accurate for most people, but all estimation methods have a margin of error (typically ±3–4%). For the most accurate results, measure in the morning before eating.