if you know how to measure the fit of a bra the width of it which is the number part is so many inches less then the bust width and the difference is what designates the lettered cup size.so the bra has a size that is still equal to what it needs to be fit that width but cup size would look bigger then say a 36 b just as a 36 b cup might look a little bigger then say a 32 b because like i tried to explain each cup is made to be a ratio to the size of the width.sorry if this doesn't really help.