Source: Two web pages, here and here. The first page suggests Maggie Q herself saw the page and didn't have any corrections…which I'm taking to mean her size (40) is accurate. It's difficult converting that to a US size because some charts say 40 is 8.5, some say 9, some say 9.5, and some say 10. I'm going to stick with 9.5 for now unless anyone else has better info.

For Maggie's height, see celebheights.com.

Maggie in shoes