I’ve looked at three possible measures: the time spent as the “official” Doctor (ie. the time between first broadcast appearance as the Doctor and their successor’s first appearance) not including Two/Three/Five Doctor stories, radio appearances etc.; the amount of Doctor Who to appear on screen with each Doctor in the lead role; and the lengevity of each incarnation within the Doctor’s own personal time line. This last is clearly the most controversial because of the difficulty in establishing the Doctor’s age at any given time. I’m fairly sure he’s 1,137 years old now (ie. just after leaving Rose). Where he’s been travelling with a human companion I’ve used their aging as a guide to the time elapsed (that’s assuming the Doctor hasn’t gone off for a few years and come back to rejoin them). The Doctor spends 180 years in his 7th and 8th incarnation and I’ve no idea at what point he regenerates (ie how old he is at the time of the TV movie) so I’ve just shared that time between them.

The First Doctor

Played by William Hartnell, Richard Hurdnall (TV Series); Peter Cushing (Films)

“Official” TV Doctor for 3 years (our time)

or approx 3,350 minutes of Doctor Who (screen time)

and 449 years (the Doctor’s time).

The Second Doctor

Played by Patrick Troughton

“Official” TV Doctor for 3 years 2 months (our time)

or approx 2,975 minutes of Doctor Who (screen time)

and around 3 years (the Doctor’s time).

The Third Doctor

Played by Jon Pertwee

“Official” TV Doctor for 5 years (our time)

or approx 2,550 minutes of Doctor Who (screen time)

and approx 296 years (the Doctor’s time).

The Fourth Doctor

Played by Tom Baker (TV Series), Jon Culshaw (Big Finish Audio)

“Official” TV Doctor for 6 years 3 months (our time)

or approx 4,300 minutes of Doctor Who (screen time)

and approx 149 years (the Doctor’s time).

The Fifth Doctor

Played by Peter Davison

“Official” TV Doctor for 3 years (our time)

or approx 1,840 minutes of Doctor Who (screen time)

and around 3 years (the Doctor’s time).

The Sixth Doctor

Played by Colin Baker, Sylvester McCoy

“Official” TV Doctor for 3 years 5 months (our time)

or approx 1,100 minutes of Doctor Who (screen time)

and 53 years (the Doctor’s time).

The Seventh Doctor

Played by Sylvester McCoy

“Official” TV Doctor for 8 years 8 months (our time)

or approx 1,015 minutes of Doctor Who (screen time)

and, er…, about 92 years (the Doctor’s time).

The Eighth Doctor

Played by Paul McGann

“Official” TV Doctor for 8 years 10 months (our time)

or approx 85 minutes of Doctor Who (screen time)

and, well, um… 90 years (the Doctor’s time).

The Ninth Doctor

Played by Christopher Eccleston

“Official” TV Doctor for 3 months (our time)

or approx 585 minutes of Doctor Who (screen time)

and about a year (the Doctor’s time).

The Tenth Doctor

Played by David Tennant

“Official” TV Doctor for at least a year (our time)

or least 625 minutes of Doctor Who (screen time)

and, er…, I dunno? (the Doctor’s time).