Body Fat Calculator (US Navy Method)

For most people it lands within a few percentage points of lab methods such as DEXA. Accuracy depends heavily on measuring the same way each time, and it is less reliable for very lean or very muscular people.

Women typically store more fat around the hips and thighs, so the women's equation adds the hip circumference to the waist to capture it. The men's equation uses waist and neck only.

Measure your neck just below the larynx (Adam's apple), with the tape sloping slightly down at the front. Men measure the waist at the navel; women at the narrowest point. Measure hips around the widest part of the buttocks. Stand relaxed and don't pull the tape tight.

Using the American Council on Exercise categories, the fitness range is 14–17% for men and 21–24% for women, and average is 18–24% for men and 25–31% for women. Men need at least about 2% and women about 10% essential fat.

It tells you more about composition. BMI uses only height and weight, so it cannot separate muscle from fat. Body fat percentage estimates how much of your weight is fat, which is why the two can disagree for muscular people.

Every two to four weeks is enough to see a trend. Measure at the same time of day, ideally in the morning before eating, and track the trend rather than any single result.