What's your body fat percentage?

How the US Navy method works

Developed by Hodgdon and Beckett for the US Navy in 1984, it predicts body fat from height and circumference measurements: neck and waist for men, plus hips for women. It needs nothing more than a tape measure, which is why it's still used for military fitness standards.

How to measure

Use a soft tape, snug but not pressing into the skin. Measure the neck just below the larynx. Men measure the waist at the navel, women at the narrowest point. Women also measure the hips at the widest point. Measure relaxed, not sucking in, and take each one twice.

How accurate is it?

For most people it lands within about 3 to 4 percentage points of lab methods such as DEXA. It is best for tracking change over time: measure the same way every few weeks and watch the trend.

The ranges shown are the American Council on Exercise's general categories for adults.

Frequently asked questions

Is this better than BMI?

It's more useful for people who train, because it separates fat from lean mass, which BMI can't.

Why does it need my neck size?

Neck size tracks with lean mass, so subtracting it from the waist helps isolate fat around the middle.

How often should I measure?

Every two to four weeks, at the same time of day, is plenty to see a trend.