While fat transfer can be used for augmentation of the breasts, the results can be inconsistent. This is true fat transfer to any region of the body, this inconsistency presents the greatest challenge in the breast. This is because asymmetric graft take will be exceedingly noticeable. Graft take is highly variable ranging from good to poor (with resorption rates sometimes reaching 50%). This range can make achieving a symmetric result much more difficult.Saline/silicone implants represent a much more reliable means of adding volume to the breasts. With regards to your sizing concerns, patients often think in terms of cup size when considering augmentation. Unfortunately, devices are sized in terms of milliliters (cc) of volume. This can lead to some confusion when sizing. Additionally, it is important to remember that cup size itself is not standardized with variations from one manufacturer to another. Unfortunately, as many women can attest their cup size in an industry leader such as VS is not necessarily transferable to another brand. Another point which is often under appreciated is that of anatomy and starting point. Any implant will add volume to the volume which is already present. The implant is additive. A particular volume will not necessarily confer the same cup size to different patients (often times it will not even confer the same cup size to different breasts in the same individual...remember they are "sisters" not "twins"). A general rule of thumb is that 125cc can represent somewhere between 1/2 to a full cup size increase. Smaller volume differentials (25-50cc) are typically less consequential representing a volume change of less than a shot glass. However, I have found these numbers, at least anecdotally, to be of little help. Patients often present with notions/goals which do not correlate with these sorts of sterile volumetric assessments. When sizing patients, there are a number of useful tools including: -3D imaging (has the added benefit of offering a volumetric analysis of the pre-operative breast) -Breast sizers (rice bags) -Goal photos I also recommend that patients commit to a particular look rather than a cup size. Once a patient settles on a look that pleases them the overall cup size increase becomes less relevant. As always, discuss your concerns with a board certified plastic surgeon (ABPS).