4/5 because they're a little wide and long. I normally were a 6.5 and got the 6, but they are still loose. That's fine though. Very comfortable. Easy to slip on and off. The cushioning is great too. It's a very springy and bouncy shoe when you walk. Definitely helps for work since I'm on my feet 14 to 16 hours a day 4 x week as a nurse.