I am a size 8.5 regularly but after reading many reviews I went with size 9. I am glad I did. I am 5'5 145lbs with very muscular calves. I love this boot, but I have kind of a hard time zipping them up with my jeans and socks.(I wear my boots over my jeans) I am hoping after more wear it will get easier as the material will relax. I must say, once they are up, the boots look great.