I'm a size 8.5 (I usually wear Nikes). I have a 9.75" foot and never wear narrow or wide shoes, but I bought 9.5 Narrow in these flats. I definitely think you should go at least one size up (I looked at their size chart and 8.5 would be 24.6cm so I wouldn't order my street shoe size because it would be too small). I was hesitant between 9 and 9.5 but so glad I went for 9.5 because my toes are comfortably up. I'm comfortable with or without socks. Since they are roomy, I'm glad I went for the slim fit. They were still a little loose, but tightening the strings helped resolve that issue.
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