I’m normally an 8 1/2 medium (was a 7 1/2 narrow until walking all over Manhattan for 18 yrs!) so my feet are just a bit on the narrow width side. I bought the 8 medium since 8 1/2’s were not available; it fit perfectly in length. I included pictures of a Crocs thong sandal Ive had for a couple of years to show the difference in fit.
https://www.amazon.com/Crocs-Womens-Swiftwater-Sandal-Sport/dp/B08W4GZF8V