Buy 10! This is the most comfortable romper I have ever worn! So easy to slip off the shoulder for the restroom, very lightweight and the material is soft and so comfortable. Love the pockets and it is flattering! I am thick through the thighs, and it has plenty of room. I am 5'11\" and wear anywhere between a 12 and 16. It hits me just above the ankle and is not tight at all. I could live in this!