In reply to Rajesh Kolakkal:
For La Sportiva, I take the average of my regular day shoes - trainers, running shoes etc - which is about a UK 10.5. I then add on 1.5 to make UK12, and that is what I am in Sportiva Winter boots - G2 and Batura II. For the EU sizing, UK 10.5 is about a 45, UK12 is a 47, so add 2.
If you generally wear a size 40 in trainers etc, then a 42 for the G2 Evo would be the one. If you're closer to a 41 in trainers, then a 43 would be the way to go. You need plenty of room for thick socks and room for toes to move around.