Sizing was a bit confusing.  9-10 or 11-12 means that I straddled the 2 sizes that are available.  10-11 size would have been perfect/  I normally wear a 10.5 dress shoe and 11 running shoe.  I don't like the flip flops to be too big, but do like a 1/4 inch longer on the toe and heel.  These fit just about the size as my foot.