This table shows the measurements of the insoles that go inside the sneakers (in millimeters).
To find your size, remove the insole from a pair of sneakers at home, measure it, and compare it with ours. 

EUR 36 37 38 39 40 41 42
USA 6 6,5 7,5 8 9 10 11
UK 3 4 5 6 7 8 9
Length
(mm)
240 246
253
260
266
272
278
Width
(mm)
81 83
85
86
88
89
90