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Army Body Fat Calculator
Your measurements
Example: male, 70 in tall, 15 in neck, 34 in waist — about 17.5% body fat, inside the Army maximum of 20% for ages 17–20.
Behind the numbers
How Army body fat is calculated
The Army does not measure body fat directly. Under Army Regulation 600-9, it uses the circumference method: a tape measure around your neck, waist, and (for women) hips, plus your height. Those numbers go into a formula built from logarithms, and the result is your estimated body fat percentage. The tape test is used when a soldier is over the screening weight for their height — pass the tape test and you meet the standard even if you are over the weight table. It is an estimate, not a scan: tape placement, breathing, and muscle mass all shift the number by a point or two, so treat it as a guide, not a medical verdict.
Worked example: log10(34 − 15) = log10(19) = 1.2788, and log10(70) = 1.8451. So 86.010 × 1.2788 = 110.0, and 70.041 × 1.8451 = 129.2. Then 110.0 − 129.2 + 36.76 = 17.5%.
Female: body fat % = 163.205 × log10(waist + hips − neck) − 97.684 × log10(height) − 78.387. Worked example: 163.205 × log10(30 + 38 − 13) − 97.684 × log10(64) − 78.387 = 163.205 × 1.7404 − 97.684 × 1.8062 − 78.387 = 284.0 − 176.4 − 78.4 = 29.2%. All measurements are in inches.
Maximums
Army maximum body fat by age
| Age group | Male max | Female max |
|---|---|---|
| 17–20 | 20% | 30% |
| 21–27 | 22% | 32% |
| 28–39 | 24% | 34% |
| 40+ | 26% | 36% |
The worked example above (17.5%) passes for every male age group, since even the strictest limit, 20% for ages 17–20, is above it. A female example — 64 in tall, neck 13 in, waist 30 in, hips 38 in — gives about 29.2%, which passes the 30% limit for ages 17–20.
Tips before you measure
Measure the waist at the navel (belly button) for men, and at the narrowest point of the waist for women — tape level, snug but not squeezing the skin.
Measure the neck just below the Adam's apple, with the tape sloping slightly down at the front, and keep your head straight.
For women, measure the hips at the widest point of the buttocks, with feet together.
Take each measurement three times and use the average; a half-inch error at the waist moves the result by about one percentage point.
Measure in the morning, before eating, and breathe out normally — holding your stomach in or measuring after a meal skews the tape test.
Good to know
Frequently asked questions
What happens if I fail the Army tape test?
You are enrolled in the Army Body Composition Program, which sets a monthly weight-loss or body-fat goal and re-checks you regularly. Failing repeatedly can block promotion, schools, and reenlistment, so it is worth taking seriously.
How accurate is the Army body fat formula?
Within about 3 to 4 percentage points of a DEXA scan for most people. It is less accurate for very muscular soldiers, because the formula cannot tell muscle from fat — big neck and waist measurements from muscle can push the estimate up.
Can I use centimeters instead of inches?
Yes, but convert first: divide centimeters by 2.54 to get inches, then enter the inch values. The formula only works when height, neck, waist, and hips are all in inches.
Is this the same formula the Navy and other services use?
Very close. The Army, Navy, and Marine Corps all use circumference formulas from the same family, with small differences in where the tape goes and in the constants. This page uses the Army's version from AR 600-9.