After reading the reviews and seeing that this ran small, I decided to go up a size. I typically like my coats to be roomier so I can wear sweaters, but I wanted something for the spring and summer when it rains and this is perfect. I would recommend that you do size up though. Even though I did size up, it fits as if I did my regular size. I'm about a size 16/18/1X (depending on the brand) and I bought a 2X in this. The arms are slightly tighter than I would like...but they aren't tight at all. I can fit several fingers in the holes when my arms are in them. I just like my coats to be a little roomier.