Below you can see the equivalence of sizes between the different sizing system in Europe, USA and United Kingdom:

cm Europe USA UK
25,5 39 6 5,5
26,1 40 6,5-7 6
26,7 41 7,5-8 7
27,4 42 8,5-9 8
28,0 43 9,5-10 9
28,7 44 10,5-11 10
29,3 45 11,5-12 11
30,0 46 12,5-13 12
30,7 47 13,5-14 13