Love this jacket! I wear a medium and purchased a medium. It fits great through the back. The arms are just a bit long. I usually cuff mine anyway or just tuck them under. I have short arms and its hard to actually find the right fit.  The only problem with this jacket is it does not come together to clasp. Not sure if i went up a size if it would change the fit as it is..yet give me the better fit in the front .