Body fat for males aged 30 to 39
Enter your height and tape measurements to estimate body fat. The example is a man in his 30s, 5 ft 10 in tall, with a 34 inch waist and a 15.25 inch neck.
How it works
The page measures everything in inches. It takes log10 of waist minus neck, multiplies by 86.010, subtracts 70.041 times log10 of height and adds 36.76. That is the male Navy estimate. This male page uses 70 inches for height, 34 for the waist and 15.25 for the neck.
Worked example
Say a man in his 30s is 5 ft 10 in tall with a 34 inch waist and a 15.25 inch neck. Start with waist minus neck: 18.75 inches. Log: 1.27300. Times 86.01: 109.491. Height log for 70 inches: 1.84510. Times 70.041: 129.233. Then 109.491 − 129.233 + 36.76 = 17.02, or 17.0 percent. That falls in the fitness range.
Common questions
What is a healthy body fat percentage?
Ranges depend on sex and goals. The American Council on Exercise lists essential fat, athletes, fitness, average and obesity ranges. At 17.0 percent, a man in his 30s at 5 ft 10 in falls in the fitness range, which spans 14 to 17 percent.
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 in his 30s, a waist of 34 inches against a height of 70 inches gives a waist-to-height ratio of 0.49.
Can I enter centimeters?
Yes. Switch the units and the page converts everything to inches before it does the math. For a man in his 30s at 5 ft 10 in, a waist of 34 inches is 86.4 cm and a neck of 15.25 inches is 38.7 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 in his 30s at 5 ft 10 in, a reading of 17.0 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 in his 30s at 5 ft 10 in the waist number is 34 inches and the neck number is 15.25 inches.