Your shapewear size is determined by your waist and hip sizes.

WAIST SIZE is taken by placing the tape measure snugly around the smallest part of your waist, following your body's natural indentation. If you're not sure where your smallest part is located, bend to the side to find it.

HIP SIZE is taken, while standing with your legs together, by placing the tape measure around the fullest part of your hips. This should be approximately 7" below your waist. The two sizes taken together determine the size of the garment. (See the Shapewear Size Chart below.)
 

BAND SIZE is taken by placing the tape measure around your torso, right underneath your breasts. Make sure that it lies flatly against your back and on a horizontal line all the way around your body. Pull it snugly to get an accurate measurement. Round the result, up or down, to the nearest whole inch.

Examples: If your measurement is 29 3/8”, round down to 29”;
If your measurement is 29 ½”, round up to 30”

Add 5” to the rounded measurement.

The result is your band size.

Examples: 29” + 5” = 34” band size; 30” + 5” = 35” band size

When the resulting band size is an odd number, place the tape measure flatly around your back and chest, directly under your arms. Use the evenly-numbered measurement closest to this result as your band size. This number should be 1” above or below the oddly-numbered band size.

CUP SIZE is taken by placing the tape measure around your back and across the fullest part of your breasts. Again, make sure that it lies on a horizontal line all the way around your body. But this time, be careful not to pull it too tightly. Round the result, up or down, to the nearest whole inch as you did to find your band size. Then, subtract your band size from this rounded measurement. The difference corresponds to your alphabetic cup size. (See the Cup Size Chart below.)

There are many different combinations of band sizes and cup sizes, so you should always try bras on before you buy them to make sure they fit properly and feel comfortable. Consult the Crossover Bra Size Chart below to see band and cup size combinations that are similar to one another. Bra sizes that appear in the same column are close substitutes for each other, and should be tried on when looking for a more comfortable alternative to a particular size.