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!
Yup! “Oh, she should probably go down a band size and up a cup size” popped into my head one day and I laughed at the absurdity.
I introduced my wife to the world of proper bra fit, because she’d never known any of it. No one taught her. Made me feel vaguely guilty of mansplaining, but it helped!