Body fat for males aged 40 to 49
A tape measure and a height are enough for the Navy method. The sample is a man in his 40s at 5 ft 10 in with a 35 inch waist and a 15.5 inch neck.
How it works
Body fat percent for males equals 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76, with all lengths in inches. The page converts centimeters for you. For a man in his 40s the base value is 19.5 inches and the height is 70 inches.
Worked example
For a man in his 40s at 5 ft 10 in the measurements are a 35 inch waist and a 15.5 inch neck. Waist minus neck is 19.5 inches. Its base 10 log is 1.29003, and times 86.01 that is 110.955. The height of 70 inches has a base 10 log of 1.84510, and times 70.041 that is 129.233. Subtract and adjust: 110.955 − 129.233 + 36.76 = 18.48. The estimate is 18.5 percent body fat, in the average 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 18.5 percent, a man in his 40s at 5 ft 10 in falls in the average range, which spans 18 to 24 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 40s, a waist of 35 inches against a height of 70 inches gives a waist-to-height ratio of 0.50.
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 40s at 5 ft 10 in, a waist of 35 inches is 88.9 cm and a neck of 15.5 inches is 39.4 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 40s at 5 ft 10 in, a reading of 18.5 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 40s at 5 ft 10 in the waist number is 35 inches and the neck number is 15.5 inches.