I ordered one of those tanks with the built-in bra, aggressively advertised on Facebook. I was surprised that I would have to buy a 4X, according to their size guide. I'm usually an XL. WELL, after a long wait, my tank arrived today and let me warn you ladies, these things are baby-size! It looks like it may fit a petite 11 year old girl. I can't get the thing on and it's hilarious - I got it stuck over my head with one arm through! The cups are tiny and lined with super cheap foam that rolls around. 4X sounds large but it is no bigger than a medium or even a small. I can't imagine how small the smaller sizes are. If you have ANY sort of a bust, I don't think this tank is a good choice.
One time, I accidentally threw an angora sweater in the dryer, and it came out about this size. I might note that I'm only reviewing this one thing I bought off the site. Other items they sell may be a better fit, but I can't say. I only know that I was looking forward to receiving this tank and now I'm sad.