The answer to your question depends on several factors. First, is to realize not all bras are made the same way. Therefore,although you may be size X in one bra, you may be a size Y in another bra made from a different manufacturer. Second, your final breast size is the size of the breast implant PLUS the size of your breast. Two patients with different breast sizes will end up with different cup sizes, even though the same breast size and style is used. Third, how wide is your chest and back? If you have a very wide chest and back, you may require a larger and wider implant to give you a proportional look. My recommendation is to try implants with a bra and examine yourself in the mirror. You may realize that a D cup will balance your body more than a C cup and vice versa. In my opinion, focusing on cup size is not as desirable as focusing on what balances your body more. Since we have been implementing this philosophy in our practice, and the patient trying the implants we recommend, our rate of re-operation due to implant size has been 0% for the past three years. Best of luck in your decision.