We suggest selecting your usual running shoe size when purchasing Lightfeet Thongs, Slides, Socks or Insoles. If you find the thong strap to be a bit too snug, it can be adjusted by gently stretching to accommodate the width of your foot. Be careful not to over stretch. For Half Sizes: If you wear a half size, we suggest opting for the next full size up. For instance, if your usual size is 8.5, please order a size 9.