When my patients ask me what size they will be after surgery, I struggle with the answer. They want me to use one of the conventional letters (A,B, DD) but these are not exact measurements (read more about why bra sizing makes no sense!). What's more, these letters do not reflect the fact that there is no one size for all.
When assessing what size to make someone, whether bigger or smaller, it's all about proportions and balance. Everything looks different depending on what it is next to. When you make the breasts bigger, the belly looks smaller, and vice versa. That seems pretty intuitive. But what is not always so immediately obvious is the fact that the same size will look different on different people. The exact size breast on a smaller, shorter, narrower woman will appear tiny on someone six feet tall and broad shouldered. The ultimate size has less to do with the bra cup in a vacuum, and everything to do with the overall proportions of the patient. If you're not looking at shoulders, hips, and height, you're not really sizing things up properly.
In terms of clothing size, most women have an overall size. The best candidates for plastic surgery are those who know and maintain their size, but have one element that is off proportion to the rest. For example, someone who has full hips and wears a medium overall but can't fill a B cup bra. That person will always have trouble finding clothing, and spend most of their dress time padding up. Another example is the mom who is a overall size small but has a weak and bulging belly that just can't crumple into a pair of regular jeans. Imbalance.
Imbalances can be obvious or subtle. The best way to know if you are imbalanced is to go one-piece shopping. If you can't buy a one piece or a bikini in a set, you are probably imbalanced. This is not an issue if it doesn't bother you, but if you're buying three sets of swimwear because nothing works as it should, it may be time to consider your surgical options. In most cases, the target is clear and the goal can be attained. The trick then is not to overshoot; and if you really want to hit a home-run, find a surgeon who can get that "fake out" result for you. If you get to the size you should have had to begin with, no one will question whether or not you came that way. If it fits, it fakes. Just another happy day at the beach. :)