Body Composition
Body Fat % (US Navy Method)
Estimate body fat percentage using the US Navy circumference method — neck, waist, height, and (for women) hip.
Last reviewed: August 2026
Result
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How this is calculated
The US Navy method estimates body fat from circumference measurements — neck and waist for men; neck, waist, and hip for women — combined with height, using a logarithmic formula developed by Hodgdon & Beckett (1984) at the Naval Health Research Center, as a low-cost alternative to skinfold calipers or hydrostatic weighing.
Accuracy compared to other methods
Studies generally place its error margin within a few percentage points of DEXA scans for most body types, though accuracy drops at the extremes (very lean or very high body fat). Measurement technique matters: circumferences should be taken snugly but not compressed, at consistent anatomical landmarks.
How to measure correctly
- Neck: just below the larynx (Adam's apple), tape sloping slightly downward at the front.
- Waist: at the navel, standing relaxed — not pulled in, not after exhaling forcefully.
- Hip (women only): at the widest point around the hips/buttocks.
- Measure in the morning before eating, and use the same tape tension each time so repeat measurements are comparable.
Worked example
Example — male, 180 cm
Neck 38 cm, waist 86 cm: the US Navy formula for men gives roughly 15–16% body fat, which falls in the "fitness/athletic" range on most body-fat charts for adult men. Changing the waist measurement by even 2–3 cm shifts the estimate noticeably — which is why consistent technique matters more than the formula itself.
Common measurement mistakes
- Inconsistent tape tension. A tape pulled tight one day and loose the next can shift the result by several percentage points with no real change in body composition.
- Measuring at the wrong landmark. Waist measured at the narrowest point of the torso instead of at the navel is a frequent source of underestimated body fat.
- Comparing single readings instead of trends. Because measurement error is real, a single result is less meaningful than the direction of change across several weeks of consistent measurements.
Why does the US Navy method need different inputs for men and women?
The original regression equations were derived separately by sex, since fat distribution patterns differ — the female formula adds a hip measurement to account for this.
Is this as accurate as a DEXA scan?
No — DEXA is a imaging-based clinical standard. The circumference method is a low-cost field estimate that tracks reasonably well with DEXA for most people but isn't a substitute for it.
My result seems too low/high compared to how I look. Why?
Re-measure carefully first — technique is the most common source of error. If the number still seems off after careful re-measurement, treat it as one estimate among several, not a definitive figure.
Sources
- Hodgdon JA, Beckett MB. "Prediction of Percent Body Fat for U.S. Navy Men and Women." Naval Health Research Center, 1984.