These run 1/2 size too small on me. I am a solid size 8 1/2 tennis shoe, normal width. I purchased that size and they were a tad small at the tip of the toe and sides. I thought about breaking them in, but after reading a few reviews those who were happiest with the shoe just went 1/2 size up and the shoe fit well, so thats what I did. Amazon made it very easy to exchange for a size 9. I thought the size 9 might me too big, but they fit perfect. I have worn them for a week and they are super comfy. They are not stretching too much, so my heels are not lifting out from the shoe. I am 3rd trimester pregnant (no swelling) and these are perfect for me, they are easy to put on and take off, very pleased with purchase.