I'm 5'6 and 120lbs and pretty slim
- Very big68%(19)60%(35)Vote53%(16)
- Very small3%(1)4%(2)Vote3%(1)
Most Helpful Guy
It is an impossible question to answer because weight doesn't necessarily determine breast size (to an extent at least). A lot of it is how weight is distributed.
If your breasts are in the K range, then it is not too large of a size. If your breasts are larger than a 30k, then it is too small.
That being said, 5'6" and 120 lbs probably means you are not a 30K based on statistics and likelihood... But anything is possible. The video linked by BellePepper would be a good video to watch for general boob size knowledge.
I'm not entirely knowledgeable in this being a guy and all, but I think there are places you can go to get fitted properly. These people will help you find a bra size right for you.4