Body fat for females aged 30 to 39
Enter your height and tape measurements to estimate body fat. The example is a woman in her 30s, 5 ft 4 in tall, with a 29 inch waist, a 37.5 inch hip and a 12.75 inch neck.
How it works
Body fat percent for females equals 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387, with all lengths in inches. The page converts centimeters for you. The neck on this female page is 12.75 inches and the height is 64 inches.
Worked example
For a woman in her 30s at 5 ft 4 in the measurements are a 29 inch waist, a 37.5 inch hip and a 12.75 inch neck. Waist plus hip minus neck is 53.75 inches. Its base 10 log is 1.73038, and times 163.205 that is 282.407. The height of 64 inches has a base 10 log of 1.80618, and times 97.684 that is 176.435. Subtract and adjust: 282.407 − 176.435 − 78.387 = 27.58. The estimate is 27.6 percent body fat, in the average range.
Common questions
Does age change the result?
The formula does not use age. The same measurements give the same estimate at any age. A woman in her 30s at 5 ft 4 in with a 29 inch waist, a 37.5 inch hip and a 12.75 inch neck gets 27.6 percent.
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 27.6 percent, a woman in her 30s at 5 ft 4 in falls in the average range, which spans 25 to 31 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 woman in her 30s, a waist of 29 inches against a height of 64 inches gives a waist-to-height ratio of 0.45.
Can I enter centimeters?
Yes. Switch the units and the page converts everything to inches before it does the math. For a woman in her 30s at 5 ft 4 in, a waist of 29 inches is 73.7 cm and a neck of 12.75 inches is 32.4 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 woman in her 30s at 5 ft 4 in, a reading of 27.6 percent could be a few points higher or lower in practice.