Unfortunately, there is no direct correlation between the amount of tissue removed and the ultimate cup size that a patient will wear after breast reduction surgery.
Before undergoing the breast reduction procedure it is very important to communicate your size goals with your surgeon. In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or “C cup” or "fake looking" means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate.
Best wishes.