Follow the sizing advice if you're between sizes. I'm a 9.5-10 but have a thin foot so I got a 9. I didn't have any space to spare on the foot bed but my foot fit perfectly. The top part is adjustable but I didn't love the buckle (it always seemed a little off). What was a deal breaker for me was when I walked it made squelching noises (seriously). Oddly enough it was the dual leather thong pice between my toes that made the sound. If I didn't work with kids I probably would've just lived with the sound (hoping it would go away). I will be sending mine back. :(