craftgrrl | Would someone measure a 10-year-old for me?

So, my 10-year-old (girl) cousin is coming to town tomorrow, and my mom just told me it's also her birthday. I made her a little purse last year (with a skull stenciled on it :D), and she loved it. So I thought I'd whip up a little wrist cuff for her, you know, to complete the en-saaahm-bleh.

But I just realized I have no idea how big I need to make this thing. She's an average-sized kid, but still, I have no clue as to the size of a 10-year-old's wrist. Would some crafty mama out there in Internet Land pretty please help me out?

Thanks in advance!