Medium fits great. The feel is odd... it keeps me kind of warm how ever it never seems to insulate very well. hard to explain. When sitting still, you are warm enough. if used for night ware.etc. but when you move, walk etc, the feel is cold, like a mild wind is sifting through the material.. over all these will be amazing for summer, . But as long johns or to keep warm ?.. no, these are for active use for sure... sweat a little as well. not 100% dry. I sleep in them some times to.