Doctor Who’s title famously demands answers from the mysterious, heroic Time Lord, but no detail is more elusive in the show than the Doctor’s age. Of course, secrecy is an obvious part of the Doctor’s mystique, but there are many reasons why audiences - and even the Thirteenth Doctor (Jodie Whittaker) herself - cannot definitively say how old she is. Certainly, a life of time travelling makes it hard to keep track of your own personal time, especially when the Doctor frequently makes extended stopovers in different dimensions and eras.
Additionally, there is a real-life reason for all of this confusion. Doctor Who remains the world’s longest-running sci-fi series, and its canon has become increasingly contradictory as it has expanded. Moreover, the Doctor’s adventures aren't limited to its 37 seasons, since multitudes of novels, comics, and audio books have embroidered every incarnation’s exploits. This has not been helped by various writers providing a range of different digits in answer to this question. Nevertheless, based on the show alone, we can still determine how old the Doctor is - albeit very roughly.
How Old Is The Thirteenth Doctor Now?
Though 2020 will see the arrival of Jodie Whittaker’s second season as the Doctor, her version of the alien hasn't yet discussed her age with her friends Ryan (Tosin Cole), Yasmin (Mandip Gill), and Graham (Bradley Walsh). As a result, we have to trace Thirteen’s seniority from her predecessors - the Eleventh (Matt Smith) and Twelfth Doctors (Peter Capaldi). Readers generally assume that the Doctor is around 900 years old - mainly because the character proclaimed that age for much of the show's modern era. Yet the Time Lord spent a long while in his Eleventh and Twelfth forms, and actually passed that milestone a while ago. Indeed, towards the end of his tenure, the Eleventh Doctor went on increasingly long adventures off screen. By the 50th anniversary special he had already surpassed his 1000th birthday.
But the Twelfth Doctor is where it gets trickier to pin down. The acclaimed episode "Heaven Sent" saw the Doctor trapped in his Gallifreyan confession dial by the Time Lords as they sought to untangle the Hybrid prophecy. The Doctor resolved to escape, yet as he struggled to break free it transpired that he had remained in the prison for much of the universe’s existence. Accounting for this sojourn - and the Doctor’s next two series of adventures - it would seem that, by "Resolution", the Thirteenth Doctor has exceeded 4.5 billion years old.
However, there are some details about the confession dial that are worth bearing in mind. The Doctor certainly recalls his experiences in the prison, but he only survived this vast stretch of time because he was being continuously killed and replicated by the dial’s teleporter. As such, fans have debated whether or not the Doctor aged in any identifiable way. Moreover, the more conservative estimation of over two thousand years old is generally touted because Doctor Who itself supports it. Season 10 saw the Twelfth Doctor inform Nardole (Matt Lucas) that he was over two thousand - which was something that he also implied to his much younger self (David Bradley) in "Twice Upon A Time."
Given that the show has followed the Thirteenth Doctor very closely since her regeneration, and left little wriggle room for off-screen adventures, it seems safe to assume that she, similarly, has two millennium’s worth of life behind her.
Breaking Down Every Doctor's Age In Doctor Who
By decoding the Doctor’s age, we witness the myriad of issues that fans face when they try to scrutinize the Doctor’s history. Be that as it may, we can still chart how the Doctor’s life has unfurled since he first stole his TARDIS – and how long he/she has spent in each regeneration - using retroactive details and mentions of his longevity throughout the show.
Certainly, this fundamental event was discussed when the TARDIS’s matrix was briefly transferred into a human body in "The Doctor’s Wife." This appears to have happened when the Doctor was 200 years old (which is still young by Time Lord standards) and in his first incarnation (William Hartnell). This Doctor studied and adventured for a while after acquiring the TARDIS, before regenerating into the Second Doctor (Patrick Troughton) due to old age. This occurred when he was roughly 450 years old, since the Second Doctor supplied this age to Victoria Waterfield (Deborah Watling) in their formative adventures together.
Then came the Third Doctor (Jon Pertwee) who once - egregiously - stated that he was thousands of years old while tangling with the Silurians. The Fourth Doctor (Tom Baker) later walked back on this claim and emphasized that he was around 750 years old in his adventures with Sarah Jane Smith (Elizabeth Sladen). The Fifth Doctor (Peter Davison) never discussed how old he was, whereas the Sixth (Colin Baker) proclaimed that he was 900 years old in "Revelation of the Daleks." Fans will also know that the Seventh Doctor (Sylvester McCoy) arrived some fifty years later in the show's timeline. Moreover, this particularly eccentric Doctor revealed that his age (953) was the same as the Rani’s (Kate O'Mara) in "Time of the Rani."
The short-lived Eighth Doctor (Paul McGann) had no chance to discuss his longevity in his one-off TV movie, but it's assumed that his age and tenure would have slotted nicely into the 150-year gap between the Fourth and Ninth Doctors (Christopher Eccleston). However, the retroactive inclusion of the War Doctor (John Hurt) disrupts this somewhat.
Indeed, "The Day of the Doctor" revealed that the War Doctor was a secret incarnation that had adventured in between the Seventh and Eighth Doctors. This anniversary special denoted that this Doctor was around 800 years old - which is in keeping with the Seventh and Ninth Doctor’s aforementioned ages. However, this doesn't account for the fact that the War Doctor would have spent hundreds of years fighting in the Time War, meaning that this is yet another irregularity in Doctor Who’s canon.
Yet with the Ninth and Tenth Doctors (David Tennant) show-runner Russell T. Davies ensured that there was some consistency with the Doctor’s age. In the Ninth Doctor’s inaugural season, the show reaffirmed that he had lived for nine centuries. When the Ninth Doctor perished after absorbing energy from the Time Vortex, the Tenth Doctor would frequently let companions know how old he had become. Certainly, the Doctor revealed that he was 906 to Wilfred Mott (Bernard Cribbins) in his final adventure. His successor, the Eleventh Doctor, initially continued this gradual aging when he disclosed that he was only one year older by the time of "Flesh and Stone." Yet over the next season, the Doctor’s age vastly escalated as he spent many years avoiding the Silence - and his own death.
As Doctor Who season 12 approaches, it remains to be seen if show-runner Chris Chibnall will shed more light on the Timeless Child mystery – or the possibility that the Doctor has been a woman before. However, it seems almost certain that Chibnall will allude to the Thirteenth Doctor’s age in some way, to help give a sense of how experienced the Doctor is, as she journeys to new, far-flung planets and periods of time.