Since I am going to pay Rome / Italy a visit this year, (not sure, if I get an audience with Pope Benedikt, hahaha), and plan to buy some gorgeous dresses, this site is totally handy:
International Dress Size Conversion
http://www.85b.org/dress_conv.php
haha, good thing, I have had Bennetton clothes before, or I would faint seeing that I am size 44 in Italy XD