Body Fat Percentage Calculator
Your weight alone does not say whether you are lean, muscular or carrying too much fat — two people can weigh exactly the same and look completely different. Body fat percentage fills that gap: it is the share of your total weight that is fat, rather than muscle, bone and water. This free calculator estimates it with the US Navy method, the tape-measure formula used by the American military, which needs only your height and a few circumference measurements. No scales, no calipers and no gym visit are required, just a soft tape measure and a minute of your time. The result comes with your category, from essential fat up to obese, and an estimate of your fat mass and lean mass in pounds, so you can see what a weight change really means. If you are losing weight, you want most of the loss to be fat; if you are gaining, you want most of the gain to be muscle. Checking your body fat percentage every few weeks shows which one is actually happening, in a way the bathroom scale never can.
Your Body Fat Results
Your estimated body fat percentage
0.0%
How to Use
- Choose imperial or metric units and select your sex — women also need a hip measurement.
- Measure your neck just below the Adam's apple, your waist at the navel for men or the narrowest point for women, and your hips at their widest point, with the tape level and snug.
- Enter your height and measurements, plus your weight if you want fat mass and lean mass.
- Click Calculate and compare your result with the category ranges below.
Worked Example
Take a man who is 5 feet 9 inches tall (69 inches), with a neck of 15 inches and a waist of 34 inches. The US Navy formula for men is 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Waist minus neck is 19 inches, and log10(19) is 1.279, while log10(69) is 1.839. So the calculation is 86.010 × 1.279 − 70.041 × 1.839 + 36.76 = 110.0 − 128.8 + 36.76 = 18.0 percent body fat. That falls in the 18 to 24 percent average range for men. At 170 pounds, that means about 30.5 pounds of fat mass and about 139.5 pounds of lean mass. If the same man lost 10 pounds of pure fat, his body fat would fall to about 12.8 percent — into the athletes range — while losing 10 pounds of muscle instead would leave his body fat percentage almost unchanged, which is exactly why this number is more useful than weight alone.
Body Fat Category Ranges
For men, the usual ranges are 2 to 5 percent essential fat, 6 to 13 percent athletes, 14 to 17 percent fitness, 18 to 24 percent average, and 25 percent and above obese. For women, the ranges are higher because women naturally carry more essential fat: 10 to 13 percent essential, 14 to 20 percent athletes, 21 to 24 percent fitness, 25 to 31 percent average, and 32 percent and above obese. Essential fat is the minimum needed for normal body functions, and dropping below it can disrupt hormones, immunity and fertility, so very low readings are a warning sign rather than a goal. Most healthy adults sit in the fitness or average bands, and moving from average toward fitness usually means a mix of strength training and a modest calorie deficit. Remember that the Navy method is an estimate, typically within 3 to 4 percentage points of a DEXA scan. Small differences in how you place the tape can shift the result, so measure carefully, in the same way each time, and pay more attention to the trend over months than to any single reading.
Frequently Asked Questions
What is a healthy body fat percentage?
For men, 14 to 24 percent is generally considered fitness to average, and for women 21 to 31 percent. Athletes are lower, at 6 to 13 percent for men and 14 to 20 percent for women. Going below the essential fat level is not healthy.
How accurate is the US Navy body fat method?
It is usually within about 3 to 4 percentage points of a DEXA scan for most people, which is good for a tape-measure method. Accuracy falls if measurements are taken loosely, over clothing, or at the wrong place on the body.
Where do I measure my waist for body fat?
For men, measure the waist at the navel, with the tape level and snug but not tight. For women, measure at the narrowest point of the waist, usually just above the navel. Do not pull the tape in and do not measure over thick clothing.
Why does the calculator need my neck measurement?
The neck measurement helps the formula allow for your overall frame size. A larger neck usually goes with a larger frame, so the same waist size means less body fat on a bigger-framed person than on a smaller-framed one.
How often should I check my body fat percentage?
Once every four to six weeks is enough. Body fat changes slowly, and daily or weekly checks mostly show measurement error and water changes. Measure at the same time of day, in the same way, for a fair comparison.