I am 5'5" and 145lbs and ordered size 7. I could've gone with the size 5, but they were actually a little shorter on me than the size 7.  After wearing them a couple of times now, I can say that they fit perfectly. I don't have a large butt, but the high waist makes my bottom look really good and I like the  Looks really great with bodysuits and short tops.  Planning to buy another pair.