Body Fat Percentage Calculator

Your body fat percentage is the share of your total weight that is fat, with the rest being lean mass: muscle, bone, organs and water. It is a more useful health signal than weight or BMI alone, because two people at the same weight can carry very different amounts of fat and muscle. The most accurate methods are lab-based, such as a DEXA scan or Bod Pod, but simple estimates from tape measurements or BMI are close enough to track progress at home.

This calculator offers two estimates. The US Navy circumference method uses tape measurements: neck and waist for men, plus hips for women, together with your height. It is the more reliable of the two because it reflects where you actually carry size.

The BMI method uses the Deurenberg equation, which estimates body fat from your BMI, age and sex. It needs no tape measure, only height, weight and age, but because BMI cannot tell muscle from fat, it is less accurate for very lean or very muscular people. Where you can, use the Navy method and keep the BMI figure as a rough cross-check.

The result is placed into a category using the American Council on Exercise (ACE) ranges, which differ for men and women because women naturally carry more essential fat. A small amount of fat is essential for health; the fitness and average bands cover most healthy people, and the highest band signals a level linked to greater health risk. Alongside the percentage, the tool shows your fat mass and lean mass in your chosen units so you can see the split in real terms.

Every at-home estimate has limits. Tape and BMI methods assume an average body shape and fat distribution, so they can be off by several percentage points for an individual. Measurement technique matters a lot: a tape held too loose or too tight, or measured at the wrong spot, changes the result more than small real changes in your body. Treat the number as a trend line, not a precise reading, and always measure the same way.

The formulas were built for average healthy adults, so they are least reliable at the extremes: very muscular or very lean bodies, older adults, and anyone whose fat sits mostly in places the tape does not capture. They are not designed for children, teenagers, pregnancy or serious athletes, who need proper body-composition testing. If any of these apply, treat the estimate cautiously and consider a professional measurement.

Use your body fat percentage to set a realistic composition goal and to feed the lean-mass-based Katch-McArdle formula in the BMR calculator, which is more accurate than height-and-age formulas when you know your body fat. Re-measure every few weeks under the same conditions and watch the trend rather than any single reading. Everything is worked out in your browser, and you can switch between metric and imperial units at any time.