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Tape Test History: How the Circumference Method Estimates Body Fat
The tape test estimates body fat from your height and a few circumference measurements instead of skinfold calipers, water-displacement tanks or scans. It is cheap, fast and needs only a tape measure, which is why the US military and many fitness programmes use it.
Where it comes from
The circumference equations were developed in the early 1980s by researchers at the US Naval Health Research Center, notably Hodgdon and Beckett, who tested them against more precise methods such as underwater weighing. The Department of Defense and its services adopted versions of the approach, and the Army and Navy tape methods are closely related. Regulations governing how and when it is used have been revised several times, so always check the current rules for your service.
The measurements
- Men: height, neck circumference and abdomen (waist) circumference measured at the navel.
- Women: height, neck, waist (at the narrowest point) and hips (at the widest point).
The formulas
All measurements are in inches and the formulas use base-10 logarithms.
- Men: body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
- Women: body fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Example, man: 70 in tall, neck 15.5 in, waist 34 in. Waist − neck = 18.5, and log10(18.5) = 1.267. So 86.010 × 1.267 = 108.99, minus 70.041 × 1.845 = 129.23, plus 36.76 = 16.5%.
Example, woman: 65 in tall, neck 13 in, waist 30 in, hips 38 in. Waist + hip − neck = 55 and log10(55) = 1.740. So 163.205 × 1.740 = 284.04, minus 97.684 × 1.813 = 177.09, minus 78.387 = 28.6%.
Measuring correctly
- Use a flexible, non-stretch tape held level and snug but not compressing the skin.
- Measure the neck just below the larynx, with shoulders relaxed.
- Breathe out normally before you read the waist.
- Take each measurement three times and use the average, as small errors have a big effect on the logarithms.
Maximum allowable body fat
Army regulation sets maximum body fat by age group. The commonly published limits for ages 17–20, 21–27, 28–39 and 40 and over are 20%, 22%, 24% and 26% for men and 30%, 32%, 34% and 36% for women. Standards and procedures can change, so confirm against the current regulation.
How accurate is it?
For most people the estimate lands within a few percentage points of reference methods such as DEXA, but individual errors can be larger. It tends to be less accurate for very muscular people, for those with unusually thick necks, and for those who store fat in unusual places. Changes over time in the same person, measured the same way, are more reliable than a single reading.
Alternatives
- Skinfold calipers, in trained hands.
- Bioelectrical impedance scales, which vary with hydration.
- DEXA or air-displacement scans for a more precise reading.
Frequently asked questions
Is the tape test the same as the Navy method?
The Army and Navy tape methods are closely related; both use circumference measurements and height with logarithmic formulas.
Can I use it if I am not in the military?
Yes, as a quick estimate. A DEXA scan or a professional assessment is more precise.
How often should I measure?
Every two to four weeks under the same conditions is enough to see a trend.
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This article is for general information only and is not financial, medical or professional advice.