Prior to purchasing my first pair of Hari Mari, I reached out to Andrea with numerous questions as I considered the correct size. I measured my feet and compared the measurement to the web site chart. By doing so the chart showed an 11 being the correct choice. However, when I conversed with Andrea and told her my athletic shoe was a 12, she recommended ordering the same size as my athletic shoe. Since I was wearing an 11 TEVA, I thought I would order an 11....... WRONG! The 11 arrived, was too small and a quick, simple exchange brought in the 12!! Andrea was Right? Thank you Andrea. :)