How to take the measurements
- Neck — just below the larynx, tape sloping slightly downward to the front. Do not flare the tape over muscle.
- Waist — for men at the navel, for women at the narrowest point, at the end of a normal exhale. No pulling in.
- Hip (women) — around the widest part of the buttocks.
Measure at the same time of day each time — morning before eating is easiest to repeat. Consistency matters more than absolute precision, because what you mostly want from this number is its trend.
How accurate is the Navy method?
Against DEXA scans, the circumference method typically lands within 3–4 percentage points, which is comparable to consumer bioimpedance scales and considerably more repeatable than calipers in untrained hands. It was designed by the Naval Health Research Center precisely to be a fast, equipment-free screen. Treat single readings loosely and trends seriously.
What the categories mean
The bands in the table are the American Council on Exercise reference ranges. Note that "average" is not a target — it is simply where the population sits. Essential fat is the floor your body needs to function; going below it is dangerous, not lean.
Frequently asked questions
Why does it need my waist and neck instead of just weight?
Because weight alone cannot tell fat from muscle. The circumference pattern — thick waist versus thin neck — tracks where fat actually accumulates, which is what the Navy formula was fitted on.
Why is the BMI-method number different?
It is a different estimate from different inputs. The BMI method only knows your height, weight and age, so it assumes an average build; the Navy method actually measures your shape. When they disagree, the tape is usually closer.
Is this medical advice?
No. The US Navy circumference method, which is an estimate rather than a body composition scan. For anything that matters clinically, a DEXA scan measures what this estimates.
Is my data stored or sent anywhere?
No. Your measurements never leave the page — which matters more here than for most tools.
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