Body Fat Calculator: Estimate Body Fat with a Tape Measure

You do not need a scale or a clinic for a rough body fat estimate. The US Navy method uses simple tape measurements. Measure your neck and waist, plus hips for women, and enter your height.

FreeNo sign-upRuns in your browserUpdated 2 Nov 2026
cm
cm
Measure just below the Adam's apple.
cm
Men: at the navel. Women: at the narrowest point.
cm
Measure at the widest point.
kg
Optional. Adds fat mass and lean mass.
Your resultLive

Educational estimate only. It is not medical advice or a diagnosis. Talk to a doctor or registered dietitian before changing your diet or exercise.

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How to use this calculator

  1. Choose your sex.
  2. Measure with a soft tape, relaxed, after breathing out. Write down centimetres.
  3. Enter height, neck and waist, plus hips if you chose female.
  4. Add your weight if you also want fat mass and lean mass.

The formula

Men: body fat % = 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 are in cm.

Worked example

A man with a height of 175 cm, a neck of 38 cm and a waist of 85 cm: waist minus neck is 47 cm. The formula gives about 16.9 percent body fat. At 75 kg that is about 12.7 kg of fat and 62.3 kg of lean mass. This falls in the fitness range.

Understanding your result

Ranges follow the American Council on Exercise: for men, essential fat to 5 percent, athletes 6 to 13, fitness 14 to 17, average 18 to 24 and higher from 25. For women the bands are 10 to 13, 14 to 20, 21 to 24, 25 to 31 and 32 and above. Tape methods can be off by 3 to 4 points.

When to use it

  • Track change over time using the same measuring routine.
  • Look beyond BMI for people with more muscle.
  • Estimate fat mass and lean mass.

Assumptions and limits

Educational estimate, not medical advice. A doctor or registered dietitian can give guidance that fits your health. Measure at the same time of day each time. The result is an estimate and can differ from DEXA or other clinical methods. Not suitable for children or pregnancy.

Frequently asked questions

How accurate is the Navy method?

It is usually within about 3 to 4 percentage points of lab methods for most people, so use it for trends.

How should I measure?

Use a flexible tape against the skin without pulling tight, and breathe out normally.

What is a healthy body fat percentage?

It depends on age and sex. The ranges shown are general fitness bands, not medical limits.

Why does the form ask for hips only for women?

The published formula for women uses hips, and the one for men does not.

Can I use it every day?

Daily changes are mostly measuring noise. Compare once every two to four weeks.