How the Navy method works
The U.S. Navy circumference method estimates body fat from a small set of tape measurements — height, neck and waist for men, plus hips for women — using logarithmic equations developed at the Naval Health Research Center. It was designed to screen large numbers of service members quickly and cheaply, and it remains one of the most practical estimation methods available: the only equipment required is a flexible tape measure.
Against gold-standard laboratory methods such as DEXA scans and hydrostatic weighing, the Navy formula typically lands within about 3–4 percentage points for most people. That is less precise than a scan, but far more consistent than most consumer body-fat scales, whose bioimpedance readings swing with hydration, food and time of day.
How to measure correctly
- Neck: measure just below the larynx (Adam's apple), with the tape sloping slightly downward at the front. Keep your shoulders relaxed.
- Waist: for men, measure at the navel; for women, at the narrowest point of the torso. Measure at the end of a normal exhale — do not suck in.
- Hips (women): measure around the widest part of the hips and glutes, feet together.
- Keep the tape snug but not compressing the skin, parallel to the floor, and take each measurement two or three times, using the average.
What your result means — and what it does not
Body fat percentage is a more meaningful health and physique metric than body weight or BMI, because it separates fat mass from everything else. Two people can weigh exactly the same and look and perform completely differently depending on how much of that weight is muscle. For lifters, tracking body fat during a cut or bulk answers the real question — am I losing fat or losing muscle? — that the bathroom scale cannot.
That said, no estimation method should be over-read. The value of the Navy method lies in tracking change over time: measure under the same conditions every two to four weeks, and trust the trend rather than any single reading. A result of 18% versus 20% on a given morning is noise; a steady drift from 24% to 19% over three months is real progress.
Note that the "essential fat" range in the table is a physiological floor, not a target — sustained body fat at those levels compromises hormones, recovery and health. This calculator is an educational tool, not medical advice; consult a healthcare professional for personalised guidance.