Hold the measuring tape at the tip of one shoulder and wrap it all the way around, so that it goes across the widest part of your shoulders. This can be challenging, unless your arms are as multi-jointed as those of a praying mantis, so you might want to ask someone to help you. Make a note of the number.
Put the center of the measuring tape behind your back and wrap it around your bust. Make sure the measuring tape goes around the widest part and keep it tight, without squeezing the girls so much that they spill over the tape. Make a note of the number.
Run the measuring tape around the narrowest part of your waist, a little above your belly button. Keep it flat against the skin, but don't try to pull it tight. You aren't in "Gone with the Wind," and the measuring tape isn't a corset. Make a note of the measurement.
Hold the measuring tape against one hip and run it all the way around, keeping it at the widest part of your booty. Make a note of the number.
Figure out your body shape based on the measurements. The inverted triangle shape has a hip measurement at least five percent smaller than that of the shoulders or bust. The rectangle shape has shoulder, bust and hip measurements within five percent of each other and a waist less than 25 percent smaller than the average of the shoulder, bust and hips. The triangle body shape has hips that are five percent wider than the shoulders or bust. The hourglass shape has shoulders and hips within five percent of each other, as well as a waist that is 25 percent smaller than the average of the shoulder, bust and hip measurements.