If you are confident that you know your U.S. shoe size and want to convert it easily, you can use this simple formula. For men’s shoe sizes, add 33 to your existing shoe size. For example, if you are a size 9, add 33 and you are likely a European size 42. For women’s U.S. shoe sizes, add 31.
Keep in mind that this is not the most accurate way of determining your Euro shoe size. However, it can help narrow down the range of Euro shoe sizes you should consider if you’re trying on shoes in a brick-and-mortar establishment. Note that Euro shoe sizes are the same for men, women and children’s footwear.