Estimated Breast Size After Breast Reduction?

Breast Reduction is a complicated procedure that is best done by those with the most training and experience. It is very difficult to determine the resultant cup size and shape based solely on the number of grams that are removed from your breast to best match your ideal breast image without an examination by a board certified plastic surgeon. Not just any board certified plastic surgeon, but one with many years of frequently performing breast reduction and lift surgeries, including different approaches, techniques and even fat transfer and implant choices if you are lacking superior breast fullness.This is because several measurements—not to mention breast characteristics such as density—are needed to determine how much and where to remove breast tissue to meet your goals. Without knowing your existing breast shape, dimensions, and the density of your breast tissue, it would be difficult to make this determination. For example, the same volume of breast tissue will weigh different amounts (measured in ounces or grams) in different people depending on its density. The existing base width of your breast and what you will ultimately want to look like will determine, in many cases, the maximal volume and weight that will need to be removed for the best result.Please click on the link below for more information!

If you have a breast reduction removing approximately 300g from your breast and you currently wear a DDD bra, it is likely that you will only reduce your breasts by 1 to 2 cup sizes, estimating a final size of between a D to a DD. This is only an estimate, and your breasts would need to be examined to give you a better idea. Many women do not wear the correct bra before surgery, and your final size would vary according to how much your breasts are being lifted too.
If you are looking to reduce your breasts for cosmetic reasons and to get an uplift, you may be perfectly happy with this amount of reduction, but if you are looking to reduce them because of current symptoms, I doubt you would get much relief with this amount of reduction.

Very difficult to say without seeing what your breasts look like and how dense they are. But that is not a significant reduction and likely would not be very therapeutic for you. I would say you may be smaller by a little more than a cup size, if you are truly the bra size you say you are.
Hope that helps.

Dr. Aldea has provided an excellent answer. It is my guess that you would achieve not more than 1-2 cup decrease  in overall breast  cup size and volume.

No one can predict the exact breast cup size you will achieve after the reduction.

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.
The patient's goal pictures are hanging on the wall, and allow for direct comparison.
I have found that this system is very helpful in improving the chances of achieving the patient's goals as consistently as possible.
 
I hope this helps.