I will list this by time-line.
Original Time-Line
Skyward Sword: 20, Reason? Because the creators said somewhere that he is the oldest Link so far.
Minish Cap: 9, Reason? Cause he looks 9.
Four Swords: 12 maybe, Reason? Cause he is toon-link, but he looks older than Minish Cap.
Ocarina of Time: 9/16, Reason? Officially stated.
Decline Time-Line
A Link to the Past: 12, Reason? He looks young to me and the guards in the original SNES version treat him like a kid.
Oracles: 12-13, Reason? Because he is the same Link from ALttP and it probably wasn't long after.
Link's Awakening: 12-13, Reason? Because it is the same Link from the Oracles, in the end of OoA he leaves on a raft, and how long do you think he spent on the raft?
Legend of Zelda: 12, Reason? Officially stated.
Adventure of Link: 15-16, Reason? Officially stated.
Adult Time-Line
Wind Waker: 9, Reason? Officially stated.
Phantom Hourglass: 9-10, Reason? Same Link from WW.
Spirit Tracks: 9-10, maybe even 8! Reason? Cause he sound younger than the WW Link.
Child Time-line
Majora's Mask: 9, Reason? Direct sequel to OoT.
Twilight Princess: 18ish, Reason? Because he is obviously older than 16.
Four Swords Adventure: 12, Reason? Cause he looks just like the original Four Swords Link.
That is all, tell me what you think of it. I may post what I think Zelda's ages are if this page is successful.
Original Time-Line
Skyward Sword: 20, Reason? Because the creators said somewhere that he is the oldest Link so far.
Minish Cap: 9, Reason? Cause he looks 9.
Four Swords: 12 maybe, Reason? Cause he is toon-link, but he looks older than Minish Cap.
Ocarina of Time: 9/16, Reason? Officially stated.
Decline Time-Line
A Link to the Past: 12, Reason? He looks young to me and the guards in the original SNES version treat him like a kid.
Oracles: 12-13, Reason? Because he is the same Link from ALttP and it probably wasn't long after.
Link's Awakening: 12-13, Reason? Because it is the same Link from the Oracles, in the end of OoA he leaves on a raft, and how long do you think he spent on the raft?
Legend of Zelda: 12, Reason? Officially stated.
Adventure of Link: 15-16, Reason? Officially stated.
Adult Time-Line
Wind Waker: 9, Reason? Officially stated.
Phantom Hourglass: 9-10, Reason? Same Link from WW.
Spirit Tracks: 9-10, maybe even 8! Reason? Cause he sound younger than the WW Link.
Child Time-line
Majora's Mask: 9, Reason? Direct sequel to OoT.
Twilight Princess: 18ish, Reason? Because he is obviously older than 16.
Four Swords Adventure: 12, Reason? Cause he looks just like the original Four Swords Link.
That is all, tell me what you think of it. I may post what I think Zelda's ages are if this page is successful.