I just moved from FL to a somewhat rainy city and have been looking for a simple but quality rain boot. After doing a bunch of research I narrowed down to the Kamik Heidi rain boot. I wear a size 8 shoe for the most part, but about 10% of the time I end up in an 8.5. I tried these in-store in size 8 and 9. I have a medium width foot, and regular calves (about 13 cm around at the thickest point). The 8 fit fine but was a little tight on the top of the foot (where laces usually sit on sneakers). The 9 fit great, the length wasn't that much different than the 8, but it was more comfortable around the foot. The calves fit fine with skinny jeans and I'm sure it'd fit fine with trousers for work. So definitely size up, even a whole size doesn't make a huge difference - won't feel too loose. Great buy!