We can, however, come to some estimation of how a breast implant of that size will grow your breast size based upon a few important factors.
1) What is your current bra cup size?
2) Will your breast implants be placed above or under the muscle?
3) Will you be using a high profile or low profile breast implant?
To the first point of current breast size, you might estimate a 350cc breast implant to increase your bust size by approximately 2 cups. As a very general rule of thumb, it is often considered that for every 175cc to 200cc in breast implant volume, a woman might experience approximately one bra cup size larger. The 350 therefore would fall into the low range of increasing your breast size by about two cups. If you currently wear a AA cup bra today, growing two cup sizes would be in the range of a C cup, for example.
The second mentioned factor of breast implant profile is important, especially in regards to your breast width. If you have a smaller bra band size such as a 32 to 34inch, for example, a higher profile breast implant is generally used in order to achieve a C cup in bra size. In general, the higher the profile, the smaller the width is of the breast implant. For women with a 36 or 38 inch bra band, a lower profile may generally be recommended.
The last factor mentioned above regards the placement of the breast implants. Most women decide to have the breast implant placed under the muscle. In this case, a slightly larger implant is needed to achieve the same result as a breast implant placed over the muscle. Many doctors suggest that the difference between the two placements may be as much as 15 to 20 per cent. In other words, a 350cc breast implant under the muscle will likely be similar to 300cc over the muscle due to the compression of the implant under the muscle.
One excellent way to estimate how your own breasts will be impacted with breast implants is to use a breast implant sizing system. The new systems available today allow you to try on a wide variety of breast implant sizes before you make your final decision.
In this case you might want to try a range of sizers from 300cc to 400cc in 50cc increments. Breast implant sizers, otherwise known as tester breast implants, are designed to be worn outside your body but within a bra. Designed with similar volume to corresponding breast implants, the sizers will give you a good idea of how these sizes will increase your bra size.
After trying on the breast implant sizers you might like the look and feel of a given breast implant size, for example 375cc or 300cc. After you show your doctor the sizer in your breast sizing bra, he might suggest that he will need to use a larger breast implant size to achieve the same effect as the sizer. This might especially be true if you are having your breast implant placed under the muscle. Again, generally speaking, you like a 400cc size, your doctor might suggest to use as much as 15 to 20 percent larger in the actual breast implant to achieve a similar look as the sizer.
These are all general estimates, of course. Only you and your doctor can make the decision on how a specific breast implant size, with a specific profile will increase your cup size.