If you wear either side of 7 1/2, it's either too big or too small. My solution after I received a L/XL was to send it back and get the S/M. It was too small, but after leaving it on my dogs travel bowl for 48 hours, it has a comfortable, snug fit. (see Pic) I wear a 7 1/2 normally, and with the stretching, really nice hat.
Rating:
[5 of 5 Stars!]