Calculate body fat percentage using the U.S. Army (AR 600-9) method and check whether the result meets current Army body fat standards for your age group.
Measure neck circumference just below the larynx. Waist at the narrowest point (navel level).
| Age Group | Male Max % | Female Max % |
|---|---|---|
| 17–20 | 20% | 30% |
| 21–27 | 22% | 32% |
| 28–39 | 24% | 34% |
| 40+ | 26% | 36% |
This uses the same circumference-based formula as the U.S. Army. Results may differ slightly from DEXA or hydrostatic methods.
The most common tape-test mistake is also the cheapest to make: letting the tape sit an inch higher or lower on the waist. At typical proportions one inch moves this estimate by about 1.8 points, enough to turn a 24-year-old man at 36 inches (20.4 percent) into one at 37 inches (22.1 percent), over the 22 percent limit for his age group. This calculator uses the neck, waist and height formula from the Army's older tape method (plus hips for women) and compares the result with the AR 600-9 limits coded into the page.
Men: body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Women: body fat % = 163.205 × log10(waist + hips − neck) − 97.684 × log10(height) − 78.387. All lengths are in inches and the logarithms are base 10. If you work in centimeters the page divides by 2.54 first. It returns 0 when waist minus neck (or waist plus hips minus neck) is zero or negative, caps the result between 0 and 60 percent, and rounds to one decimal.
The limits table uses the long-standing AR 600-9 maximums, men and women: ages 17 to 20, 20 and 30 percent; 21 to 27, 22 and 32; 28 to 39, 24 and 34; 40 and over, 26 and 36. PASS means the rounded estimate is at or below your group's limit. One important caveat: in June 2023 the Army moved to a one-site abdominal tape method (ALARACT 046/2023) and stopped collecting a neck measurement, with the older method phased out afterward. This page reproduces the older formulas, so its PASS or FAIL is an illustration, not an official determination. Check the current regulation or ask your unit's program staff.
Worked example: a 24-year-old man, 70 in tall, neck 15.5 in, waist 36 in. Waist − neck = 20.5. log10(20.5) = 1.3118, and × 86.010 = 112.82. log10(70) = 1.8451, and × 70.041 = 129.23. Body fat = 112.82 − 129.23 + 36.76 = 20.35, displayed as 20.4 percent. The limit for ages 21 to 27 is 22 percent, so the page shows PASS. Add one inch to the waist: 37 − 15.5 = 21.5, 86.010 × log10(21.5) = 114.60, and 114.60 − 129.23 + 36.76 = 22.13, shown as 22.1 percent and FAIL.
No. The page uses the older two-or-three-site formulas, while the Army has since adopted a one-site abdominal method. This tool is for general education, not an official screening. Rely on your unit's current assessment and the current AR 600-9.
If waist minus neck is zero or negative the logarithm cannot be taken, so the page shows 0. This usually points to a unit mix-up, such as typing inches into a centimeter field.
The page converts and calculates without rounding, while the older Army procedure rounded each reading to the nearest half inch. That can shift the result by a point or so in either direction.
Only roughly. The page itself notes that results may differ from DEXA or hydrostatic weighing. Circumference formulas are population-based and can miss by several percentage points for an individual, especially for very muscular or very lean builds.
Not on the strength of a web estimate. If body composition is a concern, talk with a doctor or registered dietitian. Crash dieting before a measurement is a poor idea.