I own 7 pairs of Vionics.  An assortment of sneakers, slides & booties. I generally take between a 7 & 71/2 Wide in most, but make sure to read many reviews to choose sizing.  In this sandal I am my true size 7.  I have many foot problems & these are Perfect!!!  If you tend to be a Double Wide, then these are not for you.  I'm a wide & these are Great!!  Excellent arch support, BUT BEWARE... If this is your 1st pair of Vionics you have to ease into wearing them... Only a few hours a day for a week or so & you'll be fine.  I also own many pairs of Clarks & Earth Brand shoes, but for a great supportive flip-flop you can't find a better one... Order true to size because the arch will hit you in the wrong spot & Go Easy at First