What cup size is 330 cc?

Thanks for your question.  It's not possible to predict a person's cup size based on implant size alone, for a number of reasons.  The cup size achieved with an implant of a certain volume will vary depending on each person's starting breast dimensions and size.   Also different bra brands have very different sizing - a person might wear a C-cup from one manufacturer but a D-cup from another.  A more reliable way to choose implants is to have a discussion with a plastic surgeon about your size goal, then select implants based on your breast dimensions, the surgeon's recommendations, and other techniques like trying on sizers or 3D imaging.

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” or "C or D 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.