what size bra should I buy for after implant removal?

Thank you for the question.

It will be in your best interest to wait on bra shopping until you are at least one month out of your surgery.  Unfortunately, it is not possible to predict exact cup size you will be after the removal of implants.

Generally speaking, what breasts look like after explantation  depends on several factors such as: the quality of skin elasticity (the better the elasticity the better the skin will bounce back),  the size of the implants used (the larger the implant the more trouble you may have with redundant skin), and the amount of breast tissue present at this time (which may have changed since the time of your breast augmentation). 
Life experience since your breast augmentation procedure, such as pregnancy or weight gain weight loss, will  potentially influence the factors discussed above. If you take these factors into consideration and apply them  to your specific circumstances you may get a good idea of what to expect after the implants are removed.

Best wishes.

 

The surgeon doing your surgery should put you in a supportive bra after surgery. Once all the swelling is completed, you can get measured and select the appropriate bra

In general, if the implant was properly sized and you haven't gained weight or had some other change in your breast volume, you should expect your breast to go back to the size it was before the augmentation. Even the shape often returns to the same if the breast wasn't stretched out by an implant that was too big for it or because time has passed and the breast has changed. 

It would not be wise to purchase bras before the removal any more than it would be appropriate before an augmentation. Assuming a simple removal of the implants (without a usually unnecessary capsulectomy), I would wait at least a couple weeks to allow healing and settling before trying on and buying new bras.