What is the Maximum Size of Breast Implants I Can Get?

First you will look extremely unnatural.

Second, no implant that could make you a G from an A exists that will fit the current width of your breast base, from medial pectoralis insertion to lateral breast border where the nerves come out.  If you transgress those limits, your implant may end up in your armpit, at your side, or way down below the inframmary fold.

Third, you greatly increase your chance of immediate interference with breast sensation that could be on all or part of one or both breasts and could be temporary, long lasting or permanent.

Fourth, the skin will not stretch enough to allow the implants to be placed in an initial operation.

Fifth, the skin may eventually stretch if you did it in two stages, going bigger each time, but the skin will be so thin and so prone to stretch marks, that if you ever did want to remove the implants you would have to have a surgical reduction of the excess skin. These large implants basically ruin your skin.

In other words, trying to go from an A to a G, even if it were possible, is bad for your health.

There are limitations as to what size implant can be placed  SAFELY during a breast augmentation surgery.  The largest size implant that is currently FDA approved in US is 800cc.  To go larger than that, you would need to proceed in stages.  Make sure you understand the pro's and con's of getting larger implants placed.

First, you are limited by the ability of your tissues to stretch. I do not recommend exceptionally large implants in general because of the associated problems inherent with the size and weight.  To answer your question, we have 800 cc's as the max in the US.

Just about anything is possible although what you're asking is far enough from the normal that it may require custom implants.  Realize also, that beyond a certain point increased size of the implants translates to increased complications.  Before making such a drastic change you should strongly consider a psychological consultation.  In my practice, I would insist on this prior to surgery. 

It is impossible to go from size A to G in one surgery. A large enough pocket either under or over the muscle can't be created to accommodate such a large implant. If the implants don't sit in the pocket properly they will be folded on themselves creating an unaesthetic look. Skin will stretch too much. You will develop all kinds of physical problems from such large breasts that many women seek breast reduction for that size.

There are a number of considerations when deciding on breast implant size.  One of these considerations is the size of the implant given the patient's breast envelope. Placing an implant which is too large for the patient's breast envelope will excessively stretch the skin and thin the breast tissue. In addition, this additional weight can cause neck and back pain. It is important to consult with an experienced plastic surgeon to discuss how best to augment your breasts to maximize their appearance, yet not cause any additional unwanted results.