I ordered the 40/9 too short returned for the 41/10 still too short. Have worn real authentic Birenstocks for years European size 40 compareable to 9-9.5. ran very short. Still waiting for credit to my credit card. I had to pay to return them.
Wear a 40 in original Birkenstocks so order same . Too short need 41. Tried to change before sent but wouldn't let me Now have to return.
This is my second pair of Spanish Sandal shoes. They are very comfortable and so cute.