The material is very thick and durable which is cool. I am normally a size small and if it just relies on the waist, a medium, but I purchased a x-small because I wanted it to be *tight*. It wasn't. I had a decent amount of room on the waist and butt still. Good for modest clothing I suppose. It also ended an inch over my knees and I'm 5'4 (I figured it was going to be longer, but not that long.)