I've measured two people, one at a 30C that I put in a dream angels which runs a size small in the band anyway, and one at a 30B but she was wearing a sports bra that was like a binder on her so she was probably more like a 30D/DD, and I didn't really have a choice because I was doing it on the floor. I felt so bad sending her back with a 32B and a 32C, but I put her in a PINK bra which I've heard don't run loose in the band, but I haven't actually measured any myself.

I was put in a 36A and I'm a 30FF. It was worse than I expected. It was really embarrassing because I told her I was wearing a 34DDD. If you've seen those posts where the girls are quadboobing so badly you can see their nipples, and the band is trying to escape off of their shoulders, you can probably imagine. The bbv demi bra is pretty bad on me even in a 32DDD, somehow the wires are too narrow for me, and the halfway adjustable straps make me irrationally angry. At least some of the girls in my store agree that we need f/g and 30 bands. They know how a bra is supposed to fit so usually the customers dont stay in their "measured size" during a fitting.

also, I get this sad sinking feeling when girls who come in needing a 26DD/28D anything in that ballpark and a 32A is a trainwreck on them, and the bra fitter recommends a 34AA or something ridiculously far off like that. We have a nordstrom in the mall with freya/panache/wacoal/chantelle(?)/natori/elomi/fantasie/other big bust brands with 30 bands but the fitters there are super hit or miss. There's a good one I had, the only issue with her is that she didn't have a very strong grasp on the us vs uk sizing systems.

their fit quiz hurts because they recommended the US equivalent of 28FF when I told it I was wearing a 30DDD, but they still do that ridiculous measurement method in stores. It also says "80% of the support should come from the band" but a band that stretches to ~8-9 inches more than my snug and 11 more than my btt underbust is going to fit me like a t shirt, not a bra.