Im 5'10" and 155lbs bought an XL because I have long arms however I am typically a L in jackets, it fits exactly how I want it to. This jacket was great under a waterproof layer for skiing in Montana. However was sometimes a little too warm not a bad thing at all. Recently I have been climbing outside in the uk in temps around 40 F and have been absolutley freezing when Its not my turn climbing. This is with a fleece and a base underneath. All in all its a great jacket and I wear it all the time but I've been wanting something a little warmer for those late fall climbing trips.