I'm currently a size 34 B. I'm getting implants 495cc under the muscle. What cup size will I end up in?

Patients often think in terms of cup size when considering
augmentation. Unfortunately, devices are sized in terms of milliliters (cc) of
volume. This can lead to some confusion when sizing. Additionally, it is
important to remember that cup size itself is not standardized with variations
from one manufacturer to another. Unfortunately, as many women can attest their
cup size in an industry leader such as VS is not necessarily transferable to
another brand.
Another point which is often under appreciated is that of
anatomy and starting point. Any implant will add volume to the volume which is
already present. The implant is additive. A particular volume will not
necessarily confer the same cup size to different patients (often times it will
not even confer the same cup size to different breasts in the same
individual...remember they are "sisters" not
"twins"). 
A general rule of thumb is that 125cc can represent somewhere
between 1/2 to a full cup size increase. Smaller volume differentials (25-50cc)
are typically less consequential representing a volume change of less than
a shot glass. However, I have found these numbers, at least anecdotally, to be
of little help. Patients often present with notions/goals which do not
correlate with these sorts of sterile volumetric assessments.
When sizing patients, there are a number of useful tools
including:
-3D imaging (has the added benefit of offering a volumetric
analysis of the pre-operative breast)
-Breast sizers (rice bags)
-Goal photos
With regards to your specific questions, I would suggest committing to a particular look
rather than a cup size. Once a patient settles on a look that pleases them the
overall cup size increase becomes less relevant.
As always, discuss your concerns with a board certified plastic
surgeon

 Thank you for the question.   There is no accurate/reliable/predictable correlation between size/profile breast implant utilized and cup size achieved. For example, I do not think that the generalizations of "200 cc equates to 1 cup" hold any validity or are helpful in any specific or practical way.  In my practice, I ask patients not to communicate their goals, or evaluate the outcome of the procedure performed, based on cup size references.
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, in bra sizers, and computer imaging)  as well as careful measurements (dimensional planning) 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. For example, 
I have found that the use of words such as “natural” or "D or DD 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. 
 

Thanks for posting your question.  Unfortunately cup size is not predictable after surgery.  You might have already noticed that your cup size can vary quite a bit depending where you buy your bra. In addition, your final breast volume depends on your current size plus the implant size.  If you are trying to get a sense of your final shape it is better to look at before and after pics, try on sizers with your surgeon, or do virtual imaging.