To measure abdominal circumference, locate the upper hip bone and the top of the right iliac crest. Place a measuring tape in a horizontal plane around the abdomen at the level of the iliac crest. Before reading the tape measure, ensure that the tape is snug, but does not compress the skin, and is parallel to the floor. The measurement is made at the end of a normal expiration.
It's interesting to note that the body composition chart does not take height into consideration. That means, on average, shorter people will score better in this category than taller people. The Air Force's official answer to this is that the measurement is taken above the hip bone, so bone structure or height does not play a part (the measurement is not the same as one's pants size). Additionally, the body composition charts are the same for females of all ages. Most health experts agree that age should be a factor here, because it is entirely natural for older people to have less muscle-mass than younger people.
Note: The below chart takes effect on January 1, 2010. Until then, the old body composition charts remains in effect.
The minimum score to pass this component is 12.8 (waist measurement of 35.5 inches).
Body Composition (Female - All Ages)