I received several comments on tips regarding size matching.
Although there is no foolproof method that would replace 100% fitting, it is nevertheless possible to get a shoe on his feet with some precaution.
1. Set your size in UK size
All runnings shoes are produced in Asia and factories work for different brands.To avoid the problems of correspondence, the factories are used to using UK sizes as references (for the molds and it is the most important in the production process). Then free brands to adapt these sizes to national sizes (some retain 3/4 others round to 1/2, there are no rules).
So you will have a lot more luck than a UK 10 at Ascics corresponds to a 10UK at Mizuno than a 45 in each of the brands.
2. Search for information about shoes in European or American blogs.
Many of us test the shoes on our blogs and in general it is indicated if the shoe has a very large or very small cutting. This will allow you to adjust your choice for models a little out of standard. For example for Vibram Fife fingers I do 9UK against 10UK on runnings. On the picture at the head of the article, you can see that the Inov8 are thinner than the NB, but they are the same size.
3. Remember to take half a size above if you are not sure.
I refer you to the very good advice of Stu Mittleman If our foot was to choose his shoes without going through our brain he would choose automatically shoes 1/2 to 1 size above.
With these tips you can enjoy the benefits of the internet, good deals and a more important choice to equip you!