Body fat (US Navy)
Estimate body-fat percentage from height, neck, waist, and (for women) hip circumference.
Average — healthy range for most adults.
How to measure
- Neck: below the larynx, tape slightly downward toward the front.
- Waist: at the navel for men, at the narrowest point for women. Tape parallel to the floor, exhale before reading.
- Hip: at the widest part of the hips/buttocks. Stand with heels together.
About this calculator
The US Navy circumference method was developed in 1984 (Hodgdon & Beckett) as a low-cost alternative to skinfold callipers for assessing recruits. It uses logarithmic regression against height and a few tape measurements; in adult populations it tracks DEXA within ±3–4% on average — good enough for tracking change over months, not for clinical diagnosis. Measure consistently, first thing in the morning, with the tape snug but not compressing skin.
Common questions
How accurate is the US Navy method?
On the population it was validated against (US Navy recruits), it estimates body fat within roughly ±3–4 percentage points of DEXA. Accuracy degrades for people very far from the validation population — bodybuilders, the very lean, or those carrying weight unusually high or low.
Why does the female formula need hip circumference?
Women typically store more fat around the hips than the abdomen. The female formula includes hip circumference to capture that distribution; the male formula doesn't because abdominal fat dominates and adding hip didn't improve fit in the original 1984 sample.
Should I use this number as my fitness goal?
Treat it as a trend line, not a verdict. Measure the same way every two weeks; the change matters more than the absolute number. For a goal, pick a body composition you want to maintain — most fit non-athletes are happiest in the 'fitness' bracket.