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Body Fat Calculator — U.S. Navy Method

BMI can't tell fat from muscle — body fat percentage can. All you need is a tape measure: neck and waist (plus hips for women) and your height.

Updated

kg
ft
in
cm
cm

Result

20%

Body fat about 20% — Average

Category (ACE)
Average
Fat mass
14 kg
Lean mass
56 kg
Waist-to-height ratio
0.52 (above 0.5 — higher risk)
  • U.S. Navy tape-measure method; typically within 3–4% of lab measurements. Measure the waist at the navel (men) or narrowest point (women).
  • For general information only — not medical advice. Speak to a doctor or registered dietitian for personal guidance.

For general information only — not medical advice. Consult a doctor or registered dietitian before making health decisions.

Formula

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

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

All measurements in centimetres. Developed by the U.S. Navy as a quick field estimate.

Examples

  • Man, 5 ft 9 in, neck 38 cm, waist 88 cm

    Body fat about 19.2% — Average

  • Woman, 163 cm, neck 33, waist 76, hip 98

    Body fat about 29.5% — Average

Reference table

Body fat categories (American Council on Exercise)
CategoryMenWomen
Essential fat2–5%10–13%
Athletic6–13%14–20%
Fitness14–17%21–24%
Average18–24%25–31%
Obese25%+32%+

Important information

  • Measure in the morning, relaxed, without pulling the tape tight. Neck: just below the Adam's apple. Waist: at the navel for men, narrowest point for women. Hips: widest point.
  • A waist more than half your height is linked to higher risk of diabetes and heart disease, whatever your BMI.

Frequently asked questions

How accurate is the Navy method?

Usually within 3–4 percentage points of lab methods like DEXA, if you measure carefully.

What is a healthy body fat percentage?

Roughly 10–20% for men and 18–28% for women, depending on age.

Why do women need hip measurements?

Women store more fat around the hips, so the formula includes it for accuracy.

Is this better than BMI?

It's more informative for muscular people or those with 'normal' BMI but high belly fat.

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