What would my predicted cup size be after having 400 grams removed from each breast (34J)?

For most women, removing 400 grams of tissue is a little less than one pound of tissue removed, and should decrease you at least 2 cups in size. Bras are not made to a standardized size, so it will vary. You might possibly even drop 3 cups.

Patients often think in terms of cup size. Reductions are measured in weight/gms.

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.

The average reduction is approximately 500 gms/side. This will represent a different size change on different patients/breasts.

When planning a medical reduction, the weight is the primary goal with the volume/cup size being secondary. Alternatively, a cosmetic reduction will focus primarily on volume without consideration of weight or density.

With regards to your specific question, 400 gms is fairly conservative given a large J cup size. Unless there is very little volume or glandular density, I would not expect dramatic cup size change post op (i.e. J to C).

As always, discuss your concerns with a board certified plastic surgeon (ABPS).

This is a tricky question as bra sizes can vary greatly from one manufacturer to the next. Having 400g of tissue removed will reduce your breasts multiple cup sizes. I encourage you to speak with your surgeon who will be able to offer more information after an examination.