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Body Fat Percentage Calculator

Estimate your body composition from a tape measure using the US Navy circumference method. Our fat percentage calculator works with centimetres or inches and shows your body composition category band.

What is the estimated body fat percentage?

Measured at the navel.

Enter your numbers and press Calculate — the full working appears here.

An estimate, not a measurement

The US Navy method infers body fat from body proportions. It is useful for tracking change over months, but it is not a body-composition scan and it is not medical advice. DEXA, hydrostatic weighing and air-displacement plethysmography are all far more accurate. See the full disclaimer.

The US Navy formula

The method works on the gap between your waist and neck — a proxy for how much mass sits around the middle — scaled against your height. Women's measurements include the hips, and the constants differ.

495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450

Men. All measurements in centimetres; inches are converted first.

495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.221 × log₁₀(height)) − 450

Women. The hip measurement is required.

How to take the measurements

The formula is only as good as the tape work. Measure at the same time of day each time, ideally in the morning before breakfast, and take each measurement two or three times to use the median value.

  • Neck — just below the larynx (Adam's apple), with the tape sloping slightly downward at the front. Do not flex or flare the neck muscles.
  • Waist — at the navel for men; at the narrowest point of the torso for women. Breathe out normally first and do not pull the tape tight into the skin.
  • Hips — women only, at the widest circumference around the buttocks, with feet placed together.
  • Height — without shoes, standing straight against a flat wall.

Small tape errors matter: a centimetre at the waist moves the estimate by roughly a full percentage point, so consistency between readings matters more than absolute precision. To monitor total body mass reduction alongside composition changes, use the weight loss percentage calculator.

Body fat categories

Commonly cited ranges, which differ between men and women because essential fat levels differ. They are orientation, not a prescription.

Body fat percentage categories for men and women
CategoryMenWomen
Essential fat2–5%10–13%
Athletic6–13%14–20%
Fitness14–17%21–24%
Average18–24%25–31%
Above average25%+32%+

Frequently asked questions

How is body fat percentage calculated from measurements?
This calculator uses the US Navy circumference method, which estimates body fat from your height, neck and waist — plus hips for women. It is a statistical formula fitted to population data, not a direct measurement of fat.
How accurate is the US Navy method?
Studies typically put it within about 3–4 percentage points of a DEXA scan for most people, which is reasonable for tracking change over time but not precise enough to treat as a clinical figure. It is least reliable at the extremes of body composition and for very muscular builds.
Where exactly do I measure?
Neck just below the larynx, sloping slightly downward at the front. Waist at the navel for men and at the narrowest point for women. Hips at the widest point. Keep the tape snug but not tight, and measure after breathing out normally.
What is a healthy body fat percentage?
The commonly cited ranges put fitness-level body fat at roughly 14–17% for men and 21–24% for women, with essential fat far lower. Healthy ranges vary with age, build and athletic background, so treat the bands as orientation rather than a target.
Why do men and women use different formulas?
Body fat is distributed differently, so the women’s formula includes a hip measurement and uses different constants. Using the wrong one produces a meaningfully wrong estimate.
Can I use inches instead of centimetres?
Yes — choose inches in the Units field and the calculator converts before applying the formula. Just make sure every measurement uses the unit you selected.

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