Breast and bra classification is as follows (from smallest to largest): A, B, C, D, and DD F, G, H (and larger) also exist. These biggest bra sizes are often needed by very large-breasted women, or women whose size increases with pregnancy and nursing. A training bra for developing girls (usually Tanner stage 2, 3, or 4) is also available and is smaller than the A cup. This is sometimes called AA. (also known as Double D or sometimes called E).