While shopping for shoes can be fun, making sure you get the right size and fit can be a daunting task. Different shoe brands use different sizes (and even then, they may run big or small, causing you to have to go up or down a size).
If you are not shopping in store with the help of an associate, most online shoe stores provide the guidance of a shoe size conversion chart. If you're planning on going to a store, just give the conversion chart a look before you head out to do your shopping.
For the most part, when converting from European shoe size to US shoe size, it is pretty easy. A simple way of looking at it is to simply look at the second number of European shoe size and that will be your US shoe size. For example, a 37 is a size 7. This isn't an exact science however as there are half-sizes to keep in mind but it's a good place to start.