Body Fat Percentage Calculator
A tape measure and two minutes gets you closer to your body composition than the scales ever will — as long as you treat the answer as an estimate with a real margin of error.
Estimated body fat
17%
Typical of regular exercisers.
83% of your mass is fat-free.
Measure the neck below the larynx, the waist at the navel for this formula specifically, and the hips at the widest point. Keep the tape level and snug.
Circumference methods estimate body fat from a regression, not a measurement of it. Expect agreement with a DEXA scan to within roughly three to four percentage points, and worse at either extreme. It is most useful for tracking a direction of travel over months, not for a single figure on a single day.
What the number is, and what it is not
The US Navy equations were derived by regressing circumference measurements against hydrostatic weighing in large military cohorts. They work because fat distributes in reasonably predictable patterns: a wider waist relative to neck, at a given height, generally means more fat. What they cannot do is measure fat — they infer it, which is why an unusually muscular neck or an unusually broad frame will skew the result.
Treat a single reading as approximate to within three or four percentage points. Its real value is in repetition: measure under the same conditions once a month, and the trend is far more reliable than any one figure. If you need genuine precision — for clinical or research purposes — DEXA is the accessible reference standard.
Note also that essential body fat is not a target to beat. Below roughly 6% in men and 14% in women, normal physiological function — hormonal, immune, and in women menstrual — starts to be compromised.
Related: waist-to-height ratio, calorie calculator, losing fat.