This is an incredibly important question. Some people are sure that they would like to be a full C and a mid D or a Double D. Others are more concerned that someone will notice and only want to make a conservative change.
A very important concept is that you do not want to make this decision based on a fear that someone will notice. If you want to go "incognito" wear more conservative clothing for a while. The goal is to look great in a bathing suit and a dress. Many "conservative" people are disappointed later that they didn't go large enough.
Bra cup size varies between manufacturers, styles and how you wear your bra. Different style bras fit differently. Some people wear their bra so that they bulge out of the top, others wear it so loosely that you can't find their breast inside!
Never look at someone else's choice of implant. It's what you start with--- plus what you add--- superimposed upon the shape of your own body. The same size implant may look completely different on another person.
The variation is so great that I have my patients come to the office with a flat panel sports bra and we put different size implants in the bra in front of a mirror. I encourage them to bring bathing suits, dresses, and any other clothing that they like to wear. This really gives you a good idea of what you will look like at each size.
Due to differences in clothing a "C" cup is not always a "C". Looking in the mirror and seeing what you look like 300cc bigger is simple physics! Your present chest plus 300cc has to look very similar to what you will look like with 300cc implants.
Most of the implants that are chosen by my patients are between 250cc and 675cc. Some are smaller and some larger. The largest implant available legally today is 1200cc.
Be highly aware of the width of the implants. If you place implants flat on a table, there is little difference in the height. It isn't that larger implants will stick out that much more. The reall difference is in how big the space will be between your breasts. If you have a wide rib cage and nipples placed out to the sides and you pick small implants, there will be a huge gap between your new breasts. This is usually not what you want. It isn't about your height and weight. Its about your rib cage width and where your nipples are!
What are the choices of implant positions?
The easiest surgical placement of the implant is under the breast tissue (submammary).
A slightly more difficult surgical placement is under the chest muscle (submuscular or subpectoral) but this position is associated with a lower incidence of capsule contracture and slightly less occurrence of rippling. There is more pain postoperatively than with a submammary placement.
What are the options for implant size?
The ultimate size of the breast is mainly a personal decision by the patient. Cup size is an inexact estimate of the final size since cup sizes vary with the bra manufacturer and how tight or loose the patient wears her bra as well as how much breast tissue is already present. Describing the preferred cup size does aid the surgeon, but it also helps to look at pictures or photos to show the physician the desired final look.
The most accurate method of estimating the implant size (in ounces) is to fill a plastic bag with measured amounts of water and place in a bra with the patient's estimated cup size. One can see with the bra on and covered by a sweater what the final result will approximate.
Patients most often comment that, "I wish I had gone larger," although there is a rare patient who feels she is too large.
A sports bra holds the implants against your chest like your natural tissue will. "Trying On" the implants in front of a mirror with several different outfits, in my opinion, is the best way to proceed.
Source:
http://www.webplastics.com/breast9.htm
http://www.breastimplantsusa.com/plastic-surgery-articles/breast-augmentation-faq-78.htm
