I can argue this point right now. I have measured my foot, it is 28 CM, and I have consistently bought shoes with that size in mind without fail.

Until recently, where I have been trying to order a pair of Teva sandals (I live far away from standard stores for purchasing brand name items, and often don't do it except for shoes, beds, office chairs, etc), and I got the size that compared to 28 CM. Too big. Go down a size. Still too big. 25 CM in Teva is officially 28 CM everywhere else. Why the inconsistency?