My Breast Size is a 42 D. If I Have 628 Grams Removed from Each Breast What Cup Size Will This Make Me?

Congratulations on your decision to proceed with breast reduction surgery; it is one of the most patient pleasing operations we perform.
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 that patients communicate their size goals with their 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” etc. 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.
Generally, I advise patients undergoing breast reduction surgery to go small enough to alleviate symptoms related to breast hypertrophy as much as possible while retaining as much breast tissue as necessary to maintain proportionality between the upper and lower torso.
Best wishes.

Unfortuntately, there is no good way to predict your future cup size.  There are multiple reasons for this.  First, cup sizes aren't necessarily standard and may vary from manufacturer to manufacturer and will also vary on how you are fitted for your bra.  For example, a 30D is essentially the same as a 32C.  Another thing to remember is that when a plastic surgeon says that he or she will remove 628 grams of breast tissue, it is only an estimate.  The goal of a breast reduction is to remove enough tissue to alleviate your symptoms, and leave enough behind so that you have an aesthetic and proportional breast.  Good luck!

First, it is very difficult to predict cup size from volume removal, second there are no photos to get an idea of what size the breast are now.  Everyone "wears" breasts a bit differently.  628 gms is a little more than a pound of tissue.