I love this bra when I'm wearing it. It is comfortable and has just enough padding to keep the highbeams from showing through. It also makes me look like a woman instead of a 13 yr old boy like most other sport bras tend to do. The problem is that the band is extremely tight. I would guess it is for a 32 since I can wear it comfortably, but have a terrible time getting it on and off. It doesn't give much to go over my shoulders and I feel I may dislocate one while taking it off. I ordered the small in this style along with a couple other styles because I have a horrible time finding a decent sport bra. I am 5'1" tall, 114 lbs, and wear a 32A/34AA. I'm keeping this one but am returning it's twin in a different color. I may try a medium, but fear it may be too big in the cup. The story of my life :(

EDIT: I've now owned this bra for over 6 months. After wearing this bra a few times, the band did stretch some but  not a lot. It is still really hard to get off, especially if I'm still sweaty after a workout. I have my husband help me peel it off if I need to change right away. I did end up keeping the second bra and actually bought 2 more because I haven't found another style that I like better. I really like the higher neck line on the bra so that when I'm wearing my lower cut Zumba tanks or loser workout tops, I don't have to show the world my girls if I bend over a little. If you have the fullness to fill the next cup size up, I would recommend going up a size, but if you don't, be aware that the bands are sized toward the smaller inch listed.