Here are several sizing systems in different countries.Most use the chest circumferences measurement system and cup sizes A-B-C+.
Cup and band sizes not only vary around the world but also between brands in the same country. For example, most women assume that a B cup on a 34 band is the same size as a B cup on a 36 band. In fact, bra cup size is relative to the band size, as the actual volume of a woman’s breast changes with the dimension of her chest.
Did you know that you can get bra cup sizes up to an “N“ or KK now? The biggest bra now available on the high street is KK – that’s a 20 inch cup size.