I am between an 8.5 and a 9 in shoes. Usually, 8.5 is fine, but in some brands I have to size up to a 9. Since they don't offer half sizes, I sized up to a 9 with these. They are slightly big, but not as large as I expected. I measured my foot, 26/27cm - slightly too big to size down to an 8. Since these are not winter boots and are not lined for cold weather, I can see wearing thicker socks with these and them fitting fine with those. One of the reasons I purchased these is that they have an actual sole. The sole is not just rubber, but an actual hardened sole material. My last pair of rain boots (different brand) barely lasted more than one year and the seam where the sole attaches to the heel part of the foot bed broke open. The soft rubber sole just couldn't withstand the amount of walking I did in them. For the price these seem like a great deal. The size I purchased was easy to get on and off. I like the material. They are not too heavy and the foot bed is nicely cushioned.