Calculating body fat
There are different methods for calculating and estimating body fat, as described in our calculators for body fat percentage and fat-free body mass (mistaken with lean body mass). In this particular calculator we use the U.S. Army method, used by the Department of Defense to vet applicants and during assessment of current staff.
To use this U.S. Army body fat calculator, it is best that you recruit the help of another person to take the measurements for you, so that they are as close to the army method as possible. With a flexible measurement tape measure the neck and waist at their narrowest points, and the hips at their widest. You can use feet and inches, or centimeters, depending on your preferences.
Body fat formula (U.S. Army Method)
Contrary to what some people think, body fat percentage is not calculated based on any kind of BMI calculation. It is actually based on correlations between several body circumference measures relative to a person’s height.
For men the formula is [3]:
86.01 x log10(waist – neck) – 70.041 x log10(height) + 36.76
For women the formula is [4]:
163.205 x log10(waist + hip – neck) – 97.684 x log10(height) – 78.387
All measurements are in inches. To use centimeters instead, replace 36.76 with 30.30 in the formula for men, and 78.387 with 104.912 in the formula for women.
Do I pass the army body fat requirement?
According to the U.S. Army Regulation 40–501 from 2017, Standards of Medical Fitness, the maximum allowed body fat percentage in order to join the army is presented in the table below:
Max. Allowable Body Fat Percentage
Age Male Female
17-20 26% 32%
21-27 26% 32%
28-39 28% 34%
40 and over 30% 36%
According to the U.S. Army Regulation 40–501 from 2017, Standards of Medical Fitness, the maxmimum allowed body fat percentage in order to remain a part of the army is presented in the table below:
Max. Allowable Body Fat Percentage
Age Male Female
17-20 20% 30%
21-27 22% 32%
28-39 24% 34%
40 and over 26% 36%
The goal of the Department of Defense is 18% body fat for males and 26% body fat for females. In our online calculator we will show you how much above the maximum allowable you are and how much you need to lose to meet the goal (if any).