I normally wear a Large or extra Large depending on the manufacturer. In this case I ordered an extra large to ensure it would fit as I did not not want it to be to small. Boy was I wrong the shoulders fit so tight I could not raise my arms ! My friend normally wears a medium and this jacket fits him just fine. I made the jacket a gift to him since he liked it. I would say the sizing is way off for this jacket or I received a medium mismarked as an extra large which I am assuming is the case. Either way I made a friend very happy. Not sure if I would trust backcountry with another order due to this issue.