8.5UK typically would translate to a 9.5US size. However, for me personally the sneakers did seem to run a little small. I wear a 12 in Converse Chucks, but the 12 in these were noticeably smaller - I posted a comparison pic in this thread a few weeks ago. I wear a 13 in New Balance (996, 574, etc.) and I think I'll need to size up to 13 in the EP sneakers.