The conversion of the size is always approximate cause of the different measurement systems based on different methods of calculating the length (the inches for the UK and the US, the french point for continental Europe). At the purchase time, please take as reference system the European measure. In addition, if your foot sole is wide or you have an high instep, we'll suggest you to consider the purchase in the hugher size.
Below you will find the differences between the different fits
NARROW: the shoe fits narrow. If you have a high instep, a wide plan or a fleshy foot, you probably need 1 size more.
REGULAR: the shoe has a regular fit. Generally the customer buys the size that he usually wear.
WIDE: the fit is wider than normal. In general, the customer buys one size less than the usual fit.