It’s so bad that my fiancée has some bras that say she’s a B cup and others that says she’s a D cup. In order to go bra shopping, you have to actually try them on to find out if they fit.
If I had to try on underwear to see if they fit, I might not bother with underwear at all!
You’re close! Both a 34B and a 32D would have the same measurement around their bust, but the bust size alone can’t be used to determine bra size. The rule is to increase band size by 1 increment (which is 2”) and reduce cup size by 1 increment (the letter) to maintain the same volume.
The volume of a 32D is the same as a 34C.
Exactly, bust size is very nice, but it doesn’t speak about the torso shape. And shape is what determines, whether a bra fits.