This is a general size guide. Measurements and fit will differ slightly between brands and styles.

 EU / IT
AU / US
UK
CM
36 5.5
6
3.5 22.5
37 6.5 4.5 23.5
38 7
7.5
5
5.5
24.5
39 8
8.5
6.5 25.5
40 9 7 26.0
41 9.5 7.5 26.5
42 10 8 27.0