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While most stores carry cup sizes from A to D and band sizes from 32 or 34 to 40 or 42, specialty retailers offer a much wider range of sizes. You'll also find some bras sized from small to extra large, particularly sports bras or tanks with built-in bras. A well-fitting bra is essential, both for your appearance and health, especially if you've been generously blessed.
Your bra band should fit snugly around your rib cage, in a line parallel to the floor. It should not rise up or slide down your back. A well-stocked lingerie shop will offer bras ranging from a 28 or 30 band size up to a 56 band. There are several methods for measuring bra band size. You can measure directly under the breasts and use this measurement as it is, or add between 3 inches and 5 inches to the under-bust measurement. You might also find you get a better fit by measuring under the arms, above the full bust, and using this measurement for your band size.
Cup sizes are determined by the difference between the band size and the full bust measurement. A 1-inch difference accounts for a single cup size. If you wear a 34-inch band and have a 38-inch full bust measurement, you'll need a D cup. While many stores only stock bras to a D cup or DD cup, many women need substantially larger cup sizes. After a D cup, cup sizes become more confusing. The next three cup sizes may be labeled a DD, DDD or DDDD, or they can be an E, F and G. Sizes above a G are consistently in alphabetical order. Bras manufactured in Europe may have more generously sized cups. A G cup in a U.K. brand may be the equivalent of an I cup in the United States.
Bras sized from small through extra large are designed for women with average cup sizes, typically a B cup or C cup. Compression-style sports bras may fit a slightly wider size range, from an A cup to a D cup. If you're below a 32-inch band or above a D cup and a 40-inch to 42-inch band, choose a cup-sized bra, not a basic-compression bra, for adequate support.
Bra sizing isn't an exact science. Bras vary in size, both in the band and the cup. You may find that you wear a smaller or larger size depending on brand. Try on bras, at least until you know how a brand and style fit. In some cases, you'll find that you can wear a bra with a size-smaller band if you increase the cup size, so try a 32C if you normally wear a 34B, or a 36F instead of a 38DD.