Body Fat Calculator

Estimate your body fat percentage with a tape measure, using the U.S. Navy method. See your fat mass, lean mass and how you compare.

Units
Sex
Body fat
–
Category (ACE)–
Fat mass–
Lean mass–

An estimate for adults, not a medical measurement.

U.S. Navy body fat 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
(all measurements in centimeters)

Body fat categories

CategoryMenWomen
Essential fat2–5%10–13%
Athletes6–13%14–20%
Fitness14–17%21–24%
Average18–24%25–31%
Above average25% and up32% and up

Ranges from the American Council on Exercise. Women naturally carry more essential fat than men.

Worked example

A man who is 70 in (177.8 cm) tall with a 15 in (38.1 cm) neck and a 34 in (86.4 cm) waist has an estimated body fat of about 17%, in the fitness range. At 175 lb, that is roughly 30 lb of fat mass and 145 lb of lean mass.

Tips for consistent measurements

  • Measure in the morning before eating, over bare skin.
  • Take each reading two or three times and use the average.
  • Keep the tape level all the way around and don't pull it tight.
  • Track the trend over weeks; daily changes are mostly water.

Have your body fat number? Find your fat-free mass index with the FFMI calculator, or compare with your BMI. This calculator is for general information only and is not medical advice.

Last reviewed October 2026.

Frequently asked questions

How does the U.S. Navy body fat method work?

It estimates body fat from your height and a few tape-measure readings: neck and waist for men, plus hips for women. The formula was developed by the U.S. Navy as a quick field method and is still widely used because it needs only a tape measure.

How accurate is it?

Studies typically find tape-measure methods land within about 3 to 4 percentage points of lab methods such as DEXA for most people, though error can be larger for very muscular or very lean people. Measure carefully and use the same technique each time to track change.

Where exactly should I measure?

Neck: just below the voice box, tape sloping slightly down to the front. Waist: men at the navel, women at the narrowest point. Hips (women): at the widest part of the buttocks. Stand relaxed, don't suck in, and keep the tape snug but not tight.

What is a healthy body fat percentage?

The American Council on Exercise lists about 14–24% for men and 21–31% for women as the fitness and average ranges. Athletes are often lower. The table on this page shows all the categories.

Is this a medical test?

No. It is a general estimate for adults and not a diagnosis. For an accurate measurement, ask a healthcare or fitness professional about methods such as DEXA or hydrostatic weighing.