The age of Link all really depends on the game. He's anywhere between the age of nine (9) and nineteen (19).
I don't think the age of the Hero of the Era of Light and Dark is ever mentioned, or confirmed. I may be wrong though. Timelinesplitter 19:33, June 7, 2012 (UTC)
OoT, he's 9 and 16, as Young and Adult Link. In MM, he's about 12-ish, because he's clearly grown up a bit, being able to lift Bomb Flowers and all. In TP, he's 17. In WW, he's between 9 and 12, because it says he's the same age as the Hero of Time although the hero was 16 in that timeline. In PH, it's the same as WW Link - 12, maybe a bit older. In ST, he seems maybe 12-13, since his voice is deeper. in SS, he looks older than young Links but younger than Adult Link, so I'd say about fifteen.
^ The Hero of Time has matured since Ocarina of Time in Majora's Mask. But it is explained that the events of Majora's Mask happen immediately after the events of Ocarina of Time. Which means that the Hero of Time is still nine years old. Same goes for Wind Waker and Phantom Hourglass, the Hero of Winds was also nine years old, and Phantom Hourglass takes place almost immediately after the events of Wind Waker. I agree with you on the age of the Hero Chosen By the Gods (Twilight Princess). I'm not sure of the age of the Hero of the Goddess (Skyward Sword), I think he's the oldest though...Timelinesplitter 17:18, June 11, 2012 (UTC)