Doctor Who: 10 Biggest Lies The Doctor Has Ever Told
8. How Old Is The Doctor?
1491751River Song said it best: the Doctor lies. Knowing that is rule #1 of traveling with the Time Lord. The Doctor lies. So, trying to assess the Doctor's age is a bafflingly immense task, especially as the Doctor themselves has been incredibly inconsistent in how they tell people their age.
Putting aside the Timeless Child for the moment, the First Doctor was around 236 years old when he 'borrowed' the TARDIS. This is supported when Romana says that the Fourth Doctor had been traveling in the TARDIS for 523 years, when in The Ribos Operation he was confirmed as 759 years old. However, when Idris and the TARDIS merged in the Doctor's Wife, she says that they have been traveling for 700 years. At this point, the Doctor was around 909 years old, which would make him 209 when he stole the TARDIS.
There are many more examples of this. Suffice it to say that the Doctor has never been 100% honest about his age, though he also suggests in The Day of the Doctor that he has told so many lies that he truly doesn't remember how old he is anymore. River Song looked into the Tenth Doctor's eyes and called him a young man, when he was 903. Between The Time of the Doctor and some of the Twelfth Doctor's era, hundreds of years pass.
How old is the Doctor?
Old.