I've seen a few sources say it was 300 years, but I thought that it was 300 years between the young and the "middle aged Doctor" and many more hundreds of years by the time we saw the old Doctor. Is that right or have I got it wrong?

It was at the very least 600 years

Yeah, that's what I was thinking. Probably more if you ask me, because he aged virtually nothing in 400 years before Trenzalore, so he'd have had to be there a LONG time to get a old as he did.

Well I have two theories on his ageing

1) The TARDIS helps show the ageing process down even more

2) Any spare regeneration energy a Time Lord had also helps show down the ageing process we know he had a bit left as he healed River's wrist (and that's why she was so mad as maybe that cost him a extra 100 or so years) so maybe by the time Trenzalore came around he was totally drained plus that is the reason once he was once again full of regeneration energy the first thing it was was fix his ageing problems

That second theory was actually posted on here by me a while back lol. If that's where you read it, it was me who came up with it

As he was technically on his last body, he used the last remains of his energy to slow down the aging process of his body, because there wasn't enough left to ever regenerate again. It's a good explanation, because it's pretty weird how he aged so slowly.

that's a good theory but it doesn't explain the first Doc and the War Doc? How did they age then?

The first Doctor maybe it doesn't kick in until after the first regeneration.

The War Doctor we don't know just how long the War Doctor lasted it could have been 1000 years but The Doctor just decide not to use those years on his age when he decided to forget he was ever The War Doctor

ok that does make sense and we know the others died/regenerated due to things other than old age so it all works out.

Plus with The War Doctor I have a personal theory that the elixir he took also was designed to keep him going as long as he had to but also to make him automatically regenerate once the War was over and he was no longer needed

I like that it would tie in nicely!

Someone posted on another thread that Time Lords may age differently than humans. They remain young for a long period of their life and then enter a period of rapid ageing over a fraction of time.

My theory is that all of the Doctor's age, but 11 (last body) aged much more slowly, because he was the last. Instead of storing his regeneration energy away for another regeneration, he used his last few dregs to keep his body young for longer.

It's possible that once the ageing has begun, it continues rapidly. This would mean that between "old Doctor" and "very old Doctor" may not be that long a time. It could be only 30 or 40 years.
During this time, the Doctor supposedly fights a full-on war because the Papal Mainframe has been taken over by the Daleks. I find it very hard to believe that he could fight a war against a fleet of Daleks with very little backup for centuries.

I suppose we won't know for sure until the Doctor next mentions his approximate age.


I like to think that all his incarnations age at the roughly the same rate (very slowly), perhaps with ageing speeding up near the end of the incarnation.
With regards to the War Doctor, we didn't get to clearly see him after he regenerated. All I saw was that his hair was black instead of grey. My explanation would be that fighting in the Time War, being immensely stressful, prematurely "aged" the Doctor by causing his hair to go grey (maybe with some more wrinkles). It can happen to humans so I see no reason why it couldn't happen to a Time Lord fighting in one of the universe's most bloody wars.

Except that the War Doctor specifically asked his age in order to work out how many years had passed between himself and the 11th so, if the War Doctor was already over 1200 when the 11th told him he was 1200 he would have had no way of knowing if the screwdriver calculation trick would work at all. He would certainly have brought up the discrepancy!

Also, apparently the Master only aged the 10th Doctor 100 years when he became the wizened old man in the year that never was.

I just tend to think that different incarnations age at different rates. Being exposed to the Time eddies of the Vortex just makes the effects of time on his body a bit random!

That's just an assumption, though. It may be that once his body starts to show the signs of aging the deterioration is then pretty rapid.

For all we know it could have been a thousand years or just ten years between Clara's first and second visits. There's no way to really tell.

My rationalisation of this is that as well as extending his capacity to regenerate, the Master also inhibited his Time Lord ability to age very slowly, which may be linked to the ability to regenerate.

It was mentioned in the classic series (by the Third Doctor I think) that once a Time Lord reaches the age of 200, they are no longer considered "young". I guess it's similar to how humans today are still considered "young" until they reach around 30 years of age (unless I'm wrong; I haven't reached that age yet, so I wouldn't know). This could mean that the Eleventh Doctor starts visibly aging from the end of Series 6 (when he's about 1100 years old, compared to over 900 when he started). Considering this, maybe we can make a sort of calculation to use a human lifespan as a baseline.

There are about 400 years between when the Doctor claims to be 1100 and when he appears "middle aged". Assuming that's what a human would look like at 60 years, then we could say that 30 years for a human is equivalent to 400 years for a Time Lord (and therefore that one year for a Time Lord is equivalent to 13.3 years for a human). If we make another assumption, that the "old" Doctor is what a human would be after 20 more years, then for the Doctor that would be 266.7 more years.

So the Doctor would have been on Trenzalore for 600-700 years.

That is, assuming the writers even thought this through when they thought: "Let's have the Doctor fight a war for an 'epic' amount of time."

I remember when people were posting the synopsis of the episode before it aired (which proved to be all correct) the figure given between Clara's visits was 900 years. I presume they got this figure from somewhere (since they also gave the 300 years figure correctly) so I guess this was the intended amount of time but wasn't mentioned on screen in the end.

Nonsense! Humans are still considered young until they're [looks for passport, can't remember where passport is, wife passes passport, checks passport, works out age at next birthday] 42 at least!

I really don't think that follows. Being considered young is not about how old he looks it's about his level of maturity. After 200 years from birth he would no longer be considered young. His physical appearance is irrelevant and the rate of aging has nothing to do with the speed of his maturaiton process.

References suggest that he first stole the TARDIS at an age between 200 and 236. He regenerated into the second Doctor at about 450 to 500. So he looked about 70 after 500 years in one body whereas the War Doctor looked about the same after about 100 years. So it definitely seems to me that he doesn't age at a constant rate.

Do we know how long the War Doctor was around though it could have been 100 or 1000 years (when giving his age I think like everything else The Doctor did not count his years as The War Doctor)

Plus as that wasn't a normal regeneration (he used the elixir) who knows what effect that would have plus maybe rather than use regeneration energy to slow down the years he used it to heal war wounds/injuries

What I meant was that his body doesn't start to physically decay until he reaches 200 years. Sorry, probably should have made that clearer.

In Day of the Doctor the War Doctor asked the 11th how old he was. The 11th guessed at 1200 and the War Doctor then said that there was 400 years between them. Which means he must have considered himself to be about 800 years old. Which is odd given that the 7th Doctor was 953, the ninth Doctor once said he was 900 and the tenth was between 903 and 906 but, there you go!

I figured that's what you meant but, what I'm saying is that I don't think the quote you mention refers to the physical decay of his body. It's a question of maturity and experience. If he regenerated at the age of 199 into a young Matt Smith would you expect him to start ageing after only a year?

I think the physical appearance of his body can only be related to the amount of time since he regenerated but, as we see with Capaldi, he can regenerate into a fairly old looking incarnation right from the start so, really, I don't think we can draw any conclusions from the age when a Time Lord is no longer considered young and the look of his physical body.

Does the Doctor speak in "Earth" years or "Gallifrey" years?