I usually wear a 32 F/DDD, but based on reviews, for a 34DD and it fits very well.  Im really sensitive to any bouncing, and this bra really helps to control that.  I will definitely be keeping this bra, but please be warned that the farbric that makes up the outside of the bras cups is much more rough and course than I expect from activewear.  If you have sensitive skin, you might want to give this bra a pass, or only wear it with very tight shirts to avoid chaffing under your arms.