I bought an XXXL (triple XL), even though I am not a big woman. I'm 5' 7", 150 lbs. and I wear either a 38B or 40B. The main reason I wear a bra is to stop the chaffing between my boobs and my belly when I sit, so I'm aiming for comfort rather than support. The band around my rib cage must be comfortable and the elastic should be flexible so it is not constricting during breathing and general movement. This brand was SO close, but it was a little restrictive and stiff all over. They just weren't comfortable enough for me to wear all day. Unfortunately, I'm going to return them.