It was lack of options that forced me to select too large. I ordered tts, after looking at these shoes on multiple sites, coming to Amazon since I was confident they would ship the authentic shoes. While they fit great from heel to arch, they were much too wide and long from arch to toes. The band across the top was too big to hold my feet in place, and I'm at least avg., not narrow footed at all. The inch plus of empty space from my toes to the ends of the shoes looked ridiculous. They looked like clown shoes, and were too heavy too lift my feet. IMHO, the base felt like I was wearing tire treads, but less flexible. Can't say too size down, because it all depends on heel length, the length needed to comfortably wear the thong, and how long your toes are.