"I bought my Birkenstock's online and felt that a Size 10 would be fitting based on the 41 sizing (10-10.5) guideline. Be sure to read the Birkenstock sizing/fitting guide I found on Birkenstock's website -- your foot should not touch the "foot cup" or ring around the shoe to allow for adequate comfort, and so that your foot can roll when you walk. I drove about an hour way to the closest DSW to try on an 11 and I exchanged them there. I needed to ensure a great fit and walk away (comfortably) in my new sandals! I love them, so happy they worked out for me."