"I was really nervous about what size to order because I usually wear a 7.5 or 8, but I've never been a Large in flip-flops before. I decided to order the L and I'm happy I did! They stick out about 1/2 inch behind my heel, but I think M would have been way too small. These flip-flops also run VERY narrow, so if you have wider feet these may not work well for you."