Body fat for males and females
Males and females store fat differently. The formulas and the categories differ. The table below sets the categories side by side. Enter your height and tape measurements to estimate body fat. The example is a man, 5 ft 9 in tall, with a 33 inch waist and a 15 inch neck.
How it works
Start with waist minus neck in inches. Take the base 10 log and multiply by 86.010. Take the base 10 log of height in inches and multiply by 70.041. Subtract the second result from the first and then add 36.76. For a man at 69 inches, waist minus neck is 18 inches.
Worked example
Measure first. A man at 5 ft 9 in with a 33 inch waist and a 15 inch neck gives a base of 18 inches. Take the base 10 log to get 1.25527. Multiply: 1.25527 × 86.01 = 107.966. The base 10 log of the height, 69 inches, is 1.83885. Multiply: 1.83885 × 70.041 = 128.795. Combine them: 107.966 − 128.795 + 36.76 = 15.93. Rounded, that is 15.9 percent, in the fitness range.
Body fat categories from the American Council on Exercise, in percent.
| Category | Male | Female |
|---|---|---|
| Essential fat | 2 to 5 | 10 to 13 |
| Athletes | 6 to 13 | 14 to 20 |
| Fitness | 14 to 17 | 21 to 24 |
| Average | 18 to 24 | 25 to 31 |
| Obesity | 25 or more | 32 or more |
Common questions
Why does the waist matter more than weight?
Waist size reflects fat carried around the middle, while body weight cannot tell fat from muscle. For a man, a waist of 33 inches against a height of 69 inches gives a waist-to-height ratio of 0.48.
Can I enter centimeters?
Yes. Switch the units and the page converts everything to inches before it does the math. For a man at 5 ft 9 in, a waist of 33 inches is 83.8 cm and a neck of 15 inches is 38.1 cm.
How accurate is the Navy method?
It is an estimate. It is usually within a few percentage points of more precise methods, and careful measuring matters. For a man at 5 ft 9 in, a reading of 15.9 percent could be a few points higher or lower in practice.
Where do I place the tape?
Measure the neck just below the larynx. For men measure the waist at the navel. For women measure the waist at its narrowest point and the hips at their widest. Keep the tape snug and level without squeezing. For a man at 5 ft 9 in the waist number is 33 inches and the neck number is 15 inches.
Does age change the result?
The formula does not use age. The same measurements give the same estimate at any age. A man at 5 ft 9 in with a 33 inch waist and a 15 inch neck gets 15.9 percent.