Body Fat Calculator

The US Navy method lands within roughly three to four percentage points of a DEXA scan for most people, which means a reading of 22% honestly means somewhere around 19% to 25%. That sounds vague and it is, but it is about as good as anything that does not involve a laboratory — the handheld and bathroom-scale devices that pass a current through you are not obviously better, and they change their answer depending on how hydrated you are. Use it to watch a trend over months rather than to settle on a number.

Neck: just below the larynx, tape sloping slightly down at the front. Waist: at the navel for men, at the narrowest point for women, standing relaxed at the end of a normal breath out — not held in, which is the single biggest source of a flattering wrong answer. Hip: at the widest point. Keep the tape snug enough not to sag but not tight enough to compress. Measure at the same time of day each time, ideally before eating.

Because the method works by inferring fat from where circumference exceeds what frame alone would explain, and women carry a larger and more variable share around the hips. A waist-only formula systematically underestimates for women, which is why the Navy uses a separate equation rather than one with a correction bolted on. If you are measuring somebody else, use the formula matching how their body distributes fat rather than what a form asks.

The American Council on Exercise gives rough bands: for men, 2–5% essential, 6–13% athletic, 14–17% fit, 18–24% average, 25%+ obese. For women the same bands run higher because more fat is physiologically essential: 10–13% essential, 14–20% athletic, 21–24% fit, 25–31% average, 32%+ obese. These are population averages and not targets — the low end of the athletic band is not a goal for most people, and going below the essential figure is dangerous rather than impressive.

Less well at both ends. The method assumes a fairly typical relationship between circumference and composition, so it tends to overestimate fat for heavily muscled people — a thick neck reads as frame, but a broad muscular waist reads as fat — and its error widens at higher body fat levels. If you lift seriously, expect the number to be pessimistic and watch the direction it moves rather than its value.

No. The arithmetic runs in this page, your measurements never leave the browser, and there is no account to create. Nothing is stored between visits unless you save it yourself.