Normally I need to go down a half size in this style of slip on sneaker...but read reviews and ordered my regular size (9). However I should have went with my gut and ordered the 8.5. I have somewhat wide feet and higher instep...My right foot is usually the issue, it's slightly wider than the left...anyway I needed them for a road trip and will not have time to return and replace. So I guess you really have to know your individual issues with shoes and fit. I didn't find them to run small, but that's just me. I normally wear between 8.5-9.5 depending on style of shoe.