Wear a size 7 - 8 regular underwear, 12 pants, and size Lg fits. Thin so not for shorts, and form fitting but not too tight. Not too tight around legs! Did not ride up under pants. I just had artery surgery with incisions at tops of both legs so can't wear regular underwear for a while. Wish they had cotton crouch but seams haven't bothered me. Length is to mid-thigh. Four stars only because I was hoping for a bit thicker material. Otherwise, perfect for what I need and a very good deal for pack of 12 cheerful colors.