Violet Link
the world will maintain its thin veneer of peace
It is 12.HE'S TWELVE DAMNIT!
Iwata AsksMiyamoto
Yes. When we decided to handle Link growing up from a 9-year-old child to a more mature 16-year-old, I wanted lots of characters to fulfill various roles. For example, Kaepora Gaebora is a grandfather figure who gives Link all kinds of advice and looks out for him. And since Link is a boy, I wanted girls besides Princess Zelda to show up.
Nintendo's confirmed OoT Link is 9. I'd say he looks 10, but I can live with 9. Opening of Wind Waker says he's the same age as OoT Link, so that'd be 9...honestly, though, he looks like he's 6 or 7.
Source?