I ordered a 7, I'm usually a size 7 .... There's a very tiny bit of extra room but a 6.5 would probably be too tight so I think they run mostly true to size...  They stunk when I received them.... like chemicals.... Just threw them in a garment bag and washed & dried them with some towels. They were dry in like 2 mins & smell was gone! Still fit right too. They DO NOT keep sand out. They're not something ready to wash the same off either. Washing machine & garment bag will be your friend. That being said, I did wear them alot on my cruise - they were that comfortable. And I get "I love your shoes" compliments on them too!