Q: The woman at Victoria's Secret did an excellent job at finding me the right strapless bra; she brought in both 32C and 34B. She measured me beforehead though and said I was 32C and that 34B is the "sister size"? What does that mean?
A: Basically a B cup on a 34 band is the same cup volume as a C cup on a 32 band, but the 32 band is obviously smaller than a 34 band. A lot of people do not know this or understand it, but cup size is always relative to the band size. A 30D is not only smaller on the band than say a 34D but also has a smaller cup volume, equivilent of a B cup on a 34 band. Your bra should fit comfortably on the first hook and the band should not ride up at the back. If you can pull the bra band away from the body more than an inch then you need a smaller band size and therefore will need to go up a cup size to keep the same volume. If the band is too tight and digging in, then you need to go up a band size and down a cup size to keep the same volume. Hope this helps.