The Army tape test, explained
The US Army's circumference ("tape") method estimates body fat from a log-ratio of neck and waist (plus hip for women) against height. It correlates within ~3–4% of DEXA on average — close enough for a field standard, not for clinical decisions.
AR 600-9 sets the maximum allowable body fat by age and sex. Exceeding it triggers the Army Body Composition Program. Our calculator shows the limit, your current %, and whether you pass.
The US Navy and USMC use the same underlying circumference formula. Marines must also pass a separate height/weight screen first.