I wear a size 7 1/2 so ordered size 8.  To wear a sock you will need a very thin sock, You can wear with no socks but due to the material of product your feet will sweat. They are very cushiony, I had a knee revision a year ago and have had to wear a closed shoe, however I developed heel pain on non surgical leg and needed an open back shoe. As these fit snug I have not had a shoe fly off and find they are very stable when walking. So far I am very pleased, And did I mention they are as light as air, plus smaller, not as bulky as crocs.