Based on reviews I ordered 1/2 size up 8.5 but it was a bit large.  Reordering my regular 8 although it may turn out I am between sizes and neither fits well enough.  Although the toe is round and wide, it does not have enough height, kinda flat, and this is why people are having to go up a half size.  The Vionic footbed is the only brand that uses enough arch support and heel cushion for me to be able to wear this style shoe.