The first thing to know is that breast development varies a great deal from person to person. Also while both age and genetics play a big role in how big they will get, generally speaking trans women can expect to be smaller then their closest female relatives (I was told a cup size smaller).
Besides the actual physical size of the breast, perception must be taken into consideration as well. The fact that the rib cage for the average anatomical male after puberty is bigger then it is for females means if you visually compare the two people with similar height, weight and bra size; one cissexual and one transsexual, the cissexual woman's breasts will generally appear larger.
One additional point to consider is that it is a good idea to put off any augmentation surgery until after breast development is completed. There are quite a few reasons for this but here are the most important:
- Breast development happens in spurts over a course of years! Give them a chance to grow.
- Breast development does not happen evenly... One breast may seem way smaller and but given time, it probably will catch up. Note that uneven breast size is normal, even in cissexual women.
- Breasts implants look best and most realistic when they are placed behind existing breast tissue.
- If augmentation is preformed before breast development is finished and you have additional breast growth after surgery, you run the risk of very unnatural or even deformed looking breasts.
Lastly, breast augmentation is included in the standards of care for transgender individuals but does not require the same exact criteria as SRS.
Have you had surgery? If so I would love for you to tell us about your results and experience below in the comments: