I would say it would BEST fit a 9/10, but I am an 11 or 12 wearing woman and it fit me too, I think maybe it'd be tighter on a size 13 and up, truthfully.
Just depends how you want it to fit. I wear a large or a 12 in most tops. So the smaller you are the drapier and loose it will fit. When I wore this it was mostly fitted, esp through bust, a little roomier through stomach. Hope this helps. Thanks everyone for the bids.