I am a 40E and ended up getting a Large (although an XL was recommended).  The large did fully cover my breasts with no hang over or bulge, but that is where the *decency* left off.  As soon as I put this *bra* on, it was almost like being bare chested!  There was absolutely NO support AT ALL!  I wouldn't even use this as a sleeping bra as it wouldn't even do for that.

Perhaps someone with smaller breasts would benefit from this type of *bra*, but I would suggest anyone who is bigger chested stay far FAR away from this... and stick with name brand jogging/sports bras for those days or nights you want SUPPORT without wires.