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Body Fat Calculator

A Body Fat Calculator is an easy-to-use tool that helps you estimate the percentage of fat in your body based on key measurements such as weight, height, age, gender, and sometimes waist, neck, or hip size. Unlike the scale that only shows total weight, this calculator provides a clearer picture of your body composition by distinguishing between fat mass and lean mass.

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In short

The U.S. Navy method estimates body fat from height, neck and waist (plus hips for women). Healthy ranges (ACE): men about 14–24%, women about 21–31%.

How it works

This is the US Navy circumference method: it estimates body fat from a few tape measurements instead of a scan. Men need neck and waist; women need neck, waist and hips. Height is used in both.

  1. Measure your neck below the larynx, your waist at the navel, and (for women) the hips at the widest point. Keep the tape level and do not pull it tight.
  2. The formula takes the logarithm of those circumferences — waist minus neck for men, waist plus hip minus neck for women — against height.
  3. The result is body fat as a percentage of total weight.
Typical ranges (American Council on Exercise)
CategoryMenWomen
Essential fat2–5%10–13%
Athletes6–13%14–20%
Fitness14–17%21–24%
Average18–24%25–31%
Obese25%+32%+

Expect ±3 percentage points against a DEXA scan. Measuring the same way each time matters more than the absolute number — the trend is what tells you whether a plan is working.

Examples

Worked example:

  • Man, 180 cm, neck 38 cm, waist 90 cm: the formula returns about 19.8% body fat — the "average" band, and roughly 17 kg of fat for an 85 kg body.
  • Trim the waist to 85 cm at the same height and neck and it falls to about 16.1%.

For the army's version of the same idea, with the tables used at weigh-ins, see the army body fat calculator.

These formulas are population averages published in peer-reviewed research. They cannot see your muscle mass, frame or medical history, so treat the result as a starting point and talk to a doctor or dietitian before making big changes.

Body Fat Calculator: frequently asked questions

How accurate is the Navy body fat method?
Usually within 3–4 percentage points of lab methods like DEXA, provided measurements are taken carefully.
Where do I measure my waist and neck?
Neck just below the larynx; waist at the navel for men and at the narrowest point for women; hips at the widest point.
What is a healthy body fat percentage?
ACE ranges: men — athletes 6–13%, fitness 14–17%, average 18–24%; women — athletes 14–20%, fitness 21–24%, average 25–31%.