The breast implants available for a breast augmentation come in various shapes (round and anatomic) and sizes. The choices you make regarding these factors will determine the exact nature of your results.
It is impossible to predict the exact cup size after surgery. Generally, the patient should not choose an implant that could cause problems later because the implant is too large for their frame.
Some other considerations in choosing an implant size for a breast augmentation are chest width, chest height, and base diameter (width) of the breast. For example, a patient who is six feet tall probably would not need the same size breast implants as a patient who is five feet tall.
As another example, a patient who weighs one hundred and eighty pounds would probably not be suited for the same size breast implants as a patient who weighs one hundred pounds.