I'm a big guy and pretty much fit into anything 2X. When trying on riding jackets at the cycle shop, it seemed as though I should get a 3X. All of the 2X jackets ran a bit tight...but cycle jackets are supposed to be pretty tight and fitting. I ordered this jacket in 3X thinking it would fit similarly. I think it runs a little larger than a 3X should. Just my opinion. It is athletically cut though, which is nice. And in my opinion will be a great "All Around Riding Jacket". Not too thick, not to thin. Just right.