What size cup will I end up with 255cc anatomical implant?

Thank you for the question. There is no accurate/reliable/predictable correlation between size/profile breast implant utilized and cup size achieved.  Ultimately, careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, and computer imaging) will be critical.  
Generally speaking, the best online advice I can give to ladies who are considering breast augmentation surgery ( regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals.
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, perky breasts” or "small C cup” etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on him who makes the bra; therefore, discussing desired cup size may also be inaccurate. Again, the use of computer imaging has been very helpful during the communication process, in our practice.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery, after the use of temporary intraoperative sizers.
I hope this (and the attached link, dedicated to breast augmentation surgery concerns) helps. Best wishes.

The best cosmetic result in any particular breast augmentation patient depends on a variety of factors, including: Your individual anatomy, realistic expectations, a thorough discussion with the plastic surgeon about the options, and an understanding of the pros and cons of any particular implant choice. Proper sizing is not just about the number of cc’s. The thickness of your tissue, breast dimensions which include the width, height, and projection, as well as chest wall width all need to be considered when choosing an implant. Trying on implant “sizers” of various shapes and volumes while wearing a tight t-shirt, bra, or bathing sit at a preoperative visit will help you and your surgeon choose the optimal implant.There are no manufacturers' standards for cup sizing in the bra industry. The cups of a 32 C and a 36 C are significantly different. Cup size varies from manufacturer to manufacturer and even within styles from any particular manufacturer. Nor is there a direct correlation between implant shape or size and cup size.Keep in mind that following the advice from a surgeon on this or any other website who proposes to tell you exactly what to do without examining you, physically feeling the tissue, assessing your desired outcome, taking a full medical history, and discussing the pros and cons of each operative procedure would not be in your best interest. I would suggest that your plastic surgeon be certified by the American Board of Plastic Surgery and ideally a member of the American Society for Aesthetic Plastic Surgery (ASAPS) that you trust and are comfortable with. You should discuss your concerns with that surgeon in person.Robert Singer, MD FACSLa Jolla, California

Breast Implant Size is a combination of subjective and objective criteria.There is not a direct correlation between the cc's of a breast implant and the corresponding cup size, as cup size is an inexact measurement that varies considerably among companies and even within the same company. Online consultants will not be able to guide you as well as surgeons who perform in person consultation.The size of the implants are based on a combination of a patient's goals and objectives and her anatomy. In order to provide a natural looking augmentation, the surgeon needs to evaluate many factors including soft tissue coverage, skin laxity, chest wall width, breast imprint width, the shape of the breasts and relative level of constriction to ensure that the breast implants are appropriate for your body.Consult in person with 3 experienced and expert board certified plastic surgeons to understand your options.