Running man with orthotics I'm not sure how the shoe measurement system works over there in Germany, but after buying, wearing and giving away almost a half dozen pair of these sandals, I've finally found my perfect size--thank gosh! I'm a marathon runner, and in my Mizuno marathon shoes I wear a men's size 9.5, and I wear a Birkenstock 40, although they describe this as a men's size M7. I can guarantee you the only way I would be able to wear a Birkenstock men's size M9 might be with duct tape...maybe!
Bkat Runner This is a classic comfort sandal, but be wary of RR's sizing recommendation. RR suggested a half size up, which ended up being WAY too long for me. This was exacerbated by the fact that RR's generic European size chart sized up one full size from Birkenstock's sizing chart. Great sandal, but I suggest that you go to the Birkenstock Web site to find the Birkenstock-recommended size. Needs a small break-in period as the leather straps adapt to your foot.