What it is
This tool applies the U.S. Army body-fat estimation method from Army Regulation 600-9, the basis of the Army Body Composition Program (ABCP). It uses a cloth tape measure rather than calipers or scales, so it is quick and repeatable. All measurements are in inches. This calculator is specific to the United States Army standard; civilian or other-service standards may differ.
How to use it
Select your gender. Enter your height and neck circumference. Men also enter the abdomen circumference (measured at the navel). Women enter the natural waist and the hip circumference at the widest point. Round each tape reading to the nearest half-inch as the Army does, then read the estimated body-fat percentage.
The formula explained
The method is a regression that relates the logarithm of a "circumference value" to body density. For men the circumference value is abdomen minus neck; for women it is waist plus hip minus neck. Subtracting the neck removes lean structural mass that does not reflect fat. Height appears as a negative log term because taller people distribute the same circumference over more frame.
$$\text{BF\%} = 86.010 \cdot \log_{10}\!\left(\text{Abdomen} - \text{Neck}\right) - 70.041 \cdot \log_{10}\!\left(\text{Height}\right) + 36.76$$$$\text{BF\%} = 163.205 \cdot \log_{10}\!\left(\text{Waist} + \text{Hip} - \text{Neck}\right) - 97.684 \cdot \log_{10}\!\left(\text{Height}\right) - 78.387$$
Worked example
A man 70 in tall with a 36 in abdomen and 16 in neck: abdomen − neck = 20, \(\log_{10}(20) = 1.30103\), \(\log_{10}(70) = 1.84510\). So $$\text{\%BF} = 86.010 \times 1.30103 - 70.041 \times 1.84510 + 36.76 \approx 111.892 - 129.243 + 36.76 \approx \mathbf{19.41\%}.$$
Definitions & Glossary
- Neck
- The neck circumference, measured just below the larynx (Adam's apple) with the tape sloping slightly downward to the front. The Soldier looks straight ahead with shoulders relaxed.
- Abdomen (men)
- For male Soldiers, the abdominal circumference measured horizontally at the level of the navel (belly button), taken at the end of a normal, relaxed exhalation.
- Natural waist (women)
- For female Soldiers, the waist circumference measured at the narrowest point of the torso (the natural waist), taken at the end of a normal exhalation.
- Hip (women)
- For female Soldiers, the hip circumference measured horizontally at the widest point of the buttocks, with the tape level and snug but not compressing the skin.
- Circumference value
- A body measurement taken with a tape measure around a body part, recorded in inches. The Army averages multiple readings (taken to the nearest half-inch) to reduce error.
- ABCP
- The Army Body Composition Program — the program a Soldier is enrolled in after exceeding the body-fat standard. It provides assessment, counseling, and follow-up until the Soldier returns to within standards.
- AR 600-9
- Army Regulation 600-9, the official regulation that establishes the Army Body Composition Program, the weight-for-height screening table, the tape-measurement procedure, and the maximum allowable body-fat percentages.
FAQ
Is this an exact measurement? No. The tape method estimates body fat and can vary by a few percentage points from lab methods like DEXA.
What units do I use? Inches for every measurement. Convert centimeters by dividing by 2.54.
Does the Army still use this? AR 600-9 circumference testing is the long-standing tape method; always confirm the current standard with your unit, as policies are periodically updated.
