All 8 Timelines in the Back to the Future Trilogy Explained

The Back to the Future trilogy remains one of the most popular time-travel stories in pop culture, even decades after its release. Its status as one of the best film trilogies of all time is undeniable, as it endures as a classic sci-fi story that gave many their first experience of the applications of the theory of relativity, as well as introduced many ideas that are now staples of the sci-fi genre. The trilogy’s narrative sees its characters create several different timelines, each having considerable ramifications for the lives of their past and future selves, as well as their close friends and family.

Throughout the trilogy, each new timeline is created by any instance of someone travelling into their past, as it creates a new, altered future. The science behind the movie’s time travel is written to be fairly intuitive, allowing us to easily work out how many new timelines are created over the course of the three-film arc. With that in mind, here are all 8 timelines in the Back to the Future trilogy, with their origins and key differences explained.

8) Timeline 1

The first timeline in the Back to the Future trilogy is the one that exists at the very beginning of the first movie. Marty McFly’s original timeline is largely characterized by Biff acting as his father’s unpleasant boss, and the family’s overall lack of tangible success or ambition. This is the timeline that sets all the others into motion, as it sees Doc Brown create his DeLorean time machine and effectively ends when Marty travels back to 1955 for the first time.

7) Timeline 2

The second timeline is the one that makes up almost the entirety of the first Back to the Future movie’s plot. Starting from the moment Marty arrives in the past, his actions begin to change his present in 1985. This ultimately results in his father becoming a successful author, as well as Marty and his siblings growing up to be better adjusted, and Biff working as an auto detailer instead of bullying George as he did in Timeline 1. Importantly, this timeline also eventually results in Marty McFly Jr.’s troubles in 2015, which leads Doc Brown to return to 1985 to set the events of Back to the Future Part II into motion.

6) Timeline 3

Once Doc Brown travels back to 1985 to bring Marty and Jennifer to the future, he creates Timeline 3. This is the timeline that sees Marty impersonate his son in Back to the Future Part II‘s version of 2015, and also eventually results in Marty losing his job, which is witnessed by Jennifer. This timeline is destroyed when Old Biff Tannen acts on Marty’s idea to use the sports almanac from the future to amass wealth in the past.

5) Timeline 4

Timeline 4 is the one that sees Biff become Hill Valley’s richest man, leading to a dark and unpleasant version of Marty’s present-day home. This is the timeline in which the McFly family fell apart with the murder of George McFly, the remarriage of Lorraine to Biff, and an unfamiliar family moving into the McFlys’ former home. In this timeline, Marty is sent by Biff to a boarding school in Switzerland, and it is perhaps the darkest of all the Back to the Future movies‘ 8 timelines.

4) Timeline 5

Timeline 5 is nearly identical to Timeline 4, but is characterized by only one real difference: it has duplicates of Marty and Doc Brown. This is the timeline created when Doc, Marty, Jennifer, and Einstein return from 2015 to discover that Biff had created Timeline 4 by traveling to 1955 and giving the sports almanac to his younger self. It’s only a subtle change, but the creation of a fifth timeline in that moment is one of the minor aspects that make Back to the Future such a classic sci-fi movie.

3) Timeline 6

Timeline 6 is created when Marty and Doc travel back to 1955 once again in order to prevent Biff from using the almanac to change his future. It is almost identical to Timeline 2, as Biff has yet to use the almanac to make any real differences, and is characterized by the addition of an extra Marty to the events of the first movie. It is seen only through the lens of Marty attempting to restore Timeline 2 into existence, though it ultimately sees the creation of a whole new chain of events.

2) Timeline 7

nearly identical to T2 and T6, but with 1985’s Doc Brown present in 1885 and Marty stuck in 1955 (start of BTTF3). Results in Doc’s death in 1885

Timeline 7 is largely the same as Timeline 2 and Timeline 6, except it has been subtly altered by Doc Brown’s seemingly accidental trip back to 1885 during the lightning storm. In this timeline, Doc’s arrival in 1885 has changed Timeline 6 by adding the existence of his letter, which Marty receives almost immediately after Doc’s departure. This is the timeline in which Buford Tannen kills Doc Brown after the latter has spent just a few months in 1885, ultimately leading to the events of the final movie in the Back to the Future trilogy.

1) Timeline 8

Timeline 8 is brought into existence when Marty first arrives in 1885. This is the trilogy’s final timeline, which begins with Marty’s journey into the past and follows his attempt to save Doc Brown and stand up to Buford Tannen. This is the timeline in which Doc meets Clara and the pair fall in love, eventually leading to them building a new time machine out of a steam train. The 1985 version of this timeline is widely unknown, but it hints that Timeline 8 is the one that gives Marty and Jennifer the best chance at a happy future.

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