Usually your size in other brands can be the same here.
If you don’t have any reference, you can follow the guide lines:
Place your heel against a wall and slide your foot back against the wall. Place a ruler on the floor parallel to your foot with the end of the ruler touching the wall.
Find the length from the wall to the end of your longest toe.
SIZE CONVERSION CHART
Use this length in centimeter (CM) to find your EU shoe size
Foot length (CM)
Note: if you have average / wide width feet or want a relaxed fit we recommend a size up.
View full Size Guide Instructions