Add 17 mm or 0.7 of an inch to foot size - that is the internal length for you! There is a fair amount of give here so 15 to 20 mm will be fine 0.6 to 0.8 inches - better larger than smaller so if in doubt go bigger! This item is in the category "Clothes, Shoes & Accessories\Men\Men's Shoes\Formal Shoes". The seller is "classickit-uk" and is located in this country: GB. This item can be shipped worldwide.