I found this great link because I needed to convert UK sizes when I went to London. It has lots of coversions, but I usually use the “Clothing” link.
Click on “Clothing”, then go to the “Women’s Clothing” link to enter your US size. It will automatically convert your US size to sizes in the UK, Germany, France, Italy, Australia and Japan. You can also convert your shoe size and men’s sizes as well. This is infinitely useful.