Zoiechic, I don't know if this will be helpful, but a size small fits me in the cashmere tee. I am 5'9". The sleeves are long enough, and the shoulder fit is okay. I have fairly broad shoulders compared to the rest of me. I take a medium in the Tippi sweater to get the shoulders to fit right. If I want a more fluid fit, I can also wear a medium in the cashmere crew. The sleeves will be baggy though. For comparison sake, when I look at sizes, I typically take a US size 4, or designer size 6 or 4 depending on how long they make the sleeves, and how they cut the shoulders and hips. If there are listed measurements, I look for the closest to 34-26-36. Those are not my personal measurements, but those are often the sizing measurements that work on a garment I would purchase.
I also think these sweaters may run long in the torso because they fit me well, and I have a long torso. They don't make these in a tall size.
I would say many JCrew items run large, I am not sure these do. I think these run more true to size.
