I ordered a small and medium to be sure I got the right size. They actually both fit! Because of the stretch and the loose fit, don't worry too much about being between sizes. I'm 5'6\", 120 lbs; often wear a small but I kept the medium (although could have kept the small). And I love the fabric. It's is very soft and stretchy but it is not that shiny kind of polyester looking stuff. These are so much more comfortable than leggings for lounging, and actually are very much in style with the wider leg, so they're also versatile. I'm pretty happy to find the perfect travel/lounge pant.