Body fat calculator (US Navy method)

How to take your measurements

The method is only as good as your measurements. Measure in the morning, before eating, standing up and relaxed, without sucking in your stomach. Use a flexible tape, snug against the skin but not tight, and take each measurement two or three times to use the average.

1. Height: barefoot, with your back against a wall.
2. Neck: just below the larynx (Adam's apple), with the tape sloping slightly downward at the front.
3. Waist: for men, at the navel; for women, at the narrowest part of the abdomen. At the end of a normal exhale.
4. Hips (women only): at the widest part of the buttocks.

The US Navy formula

It was developed by Hodgdon and Beckett in 1984 for the Naval Health Research Center, and the Navy still uses it in its physical assessments. It estimates fat from the relationship between your abdominal circumference (where fat builds up most), your neck (which grows mostly with muscle) and your height.

Is it accurate?

Compared with DEXA, the Navy method is usually within about ±3–4 percentage points for most people. It works worse at the extremes: it tends to overestimate fat in very muscular people with thick necks and underestimate it in people who store fat where the tape doesn't measure. For tracking your progress it's useful, as long as you measure the same way every time.

This calculator gives an estimate for guidance, not a diagnosis. If you have questions about your health, talk to a healthcare professional.

Beyond a number

A percentage doesn't tell you where your fat is or what your muscle looks like. From a single photo, Gymia's analysis estimates your body fat and also scores your definition, your muscle groups and your proportions, so you can see what to improve and track your progress with comparable photos.