I desperately want this bra to work for me, but the band is just too tight for my underbust (26.5" break-the-tape tight, 27" normal). I typically wear a 28FF bra, and the band is definitely a size to small, and I think the cups are a size too big, so I would say it fits probably more like a 26GG. Please check the measurements, however, as this is just my best guess.