How many grams do I need to be removed to be a B cup?

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 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” 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.

There are several different reasons why it can be very difficult to predict how many grams should be removed from any breast to achieve any cup size. First of all there are no absolute standards for what cup sizes should be and every manufacturer has a lot of leeway in assigning cup sizes to their different bras. Secondly, different women wear their bras differently and will choose different cup sizes for the same sized breast depending on what their personal preferences are. Also, different breasts have different densities so the same volume can have different weights for different individuals. Finally, we have no idea what size your breasts are to begin with so we cannot begin to guess how much weight might possibly be removed. The bottom line is that I would encourage you to have thorough consultation with a board certified plastic surgeon who can examine you and help you answer some of these questions. Good luck!