In Back to the Future - Part II, Biff brings a copy of Gray's Sports Almanac back to his earlier self in 1955.

Old Biff: [about the copy of "Grey's Sports Almanac" from the future] The information in here is worth millions. And I'm giving it to you.

Young Biff: [sarcastically] That's very nice. Thank you very much. Now, why don't you make like a tree and get outta here?

Old Biff: [smacks his younger self] It's "leave", you idiot! "Make like a tree, and leave"! You sound like a damn fool when you say it wrong!

Young Biff: All right, then leave! And take your book with you!

Old Biff turns on the car radio and as they listen to the final seconds of a football game, dares Young Biff to bet a million dollars that the currently losing team will win 19 to 17. When the sports announcer calls off the final score, Young Biff is convinced.

So Young Biff starts betting heavily and makes millions as a young man. But wouldn't his "luck" run out after a while?

Several possible outcomes can occur from just a few small changes caused by Biff using the sports almanac. Here are some.

  1. Middle-aged Biff buys a winning professional sports team and mismanages it into bankruptcy and fires all the players and managers who he doesn't like. The once winning team now loses one game after another. Biff loses lots of money. (And is eventually caught betting against his own team.)

  2. Because of the Butterfly Effect in Chaos Theory, if you make a small change at any point in history, and eventually those small changes affect more and more events until the timeline no longer looks like what it could have become. Biff sneezes, which leads to a freak snowstorm a few months later that strands a sports team from going to its next game. The game is cancelled and anybody who bet heavily on it loses big time. Biff loses money.

  3. A football player who would have signed up for the Dallas Cowboys joins the Denver Broncos instead after word gets out that Biff, "the luckiest man in the world", bet heavily against the Cowboys for the entire season. The player's decision affects the outcome of all games played by both the Cowboys and the Broncos for all future seasons. Biff loses money.

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    You're right that any change to the past can change the future, it's just that in this case it didn't. At least not to the point where it's affected Biff. What you're essentially saying is "Shouldn't this have happened because I think it should!" Where the reality is that it didn't happen because the writer(s) didn't think it should.
    – Möoz
    Feb 13, 2017 at 2:24
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    Who's to say it didn't? Hill Valley changed, so could something else. By the time it matters, he has the money to make more money. Showing Hill Valley's change is more dramatic than explaining Chaos Theory and a few random losses on excessive snowstorms though.
    – Radhil
    Feb 13, 2017 at 2:28
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    BttF doesn't seem to subscribe to a Butterfly Effect model of time travel. The first movie made some significant changes to Marty's life, but he still lived in the same house and had the same girlfriend, and the encounter with the Libyans was identical. There's obviously some sort of stabilizing influence at play, perhaps similar to Poul Anderson's Time Patrol series - only trivial changes are allowed, until you reach a tipping point and suddenly everything changes. Feb 13, 2017 at 5:21
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    @PaulD.Waite The Butterfly Effect is not just another fictional supposition about how time travel might work. It has nothing to do with time travel. It's not fictional since there are dozens of peer-reviewed scientific articles about it, including direct observations of it.
    – RichS
    Feb 13, 2017 at 8:20
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    @RichS: I take your point — but applying it to time travel seems like it’s fictional, given that time travel is fictional. Feb 13, 2017 at 14:36

3 Answers 3


Remember that when time travel causes changes in Back to the Future, there's a "ripple" that adjusts the timeline, and it even affects people and objects that have been displaced in time - for example, Marty slowly vanishing in the first film as his history becomes rewritten, or the gravestone in Back to the Future part III showing the various individuals slated to die based on the current course of history.

So why wouldn't this affect the sports guide? As Biff changes history with his amazingly accurate bets, it's possible that some of the game results change, but then he just has to wait until his guide catches up and shows what the new result will be.

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    An excellent answer. Note that (nu)Biff wouldn't need to wait since he'd be "updating" at the same rate as the Almanac. To him it would seem seamless and he'd have no memory of the changes.
    – Valorum
    Feb 13, 2017 at 10:36
  • @Valorum - Marty and Doc could see the photo of the gravestone in BTTF 3 updating though, their memories didn't adjust so that they remembered "always" having seen the new image. One could argue that this is because they were time travelers, but in part 1 Doc in 1955 could see the changes in Marty's photo of his siblings even though he hadn't done any time traveling yet. So I think it would be more in keeping with these "rules" if the Biff of the "A" timeline could potentially see the almanac changing, but it might never have changed so while he was looking at it so he just didn't notice.
    – Hypnosifl
    Oct 3, 2021 at 17:46

He probably did not have to keep betting on sports outcomes.

This is explained at "Biff Tannen" museum where Marty watches a clip about Biff's rise to fortune.

[Narrator] See Biff's humble beginnings, and how a trip to the racetrack on his twenty-first birthday made him a millionaire overnight.

Share in the excitement of the fabulous winning streak that earned him the name "The Luckiest Man on Earth".

Learn how Biff parlayed that winning streak into the vast empire Biffco.

Discover how in 1979 Biff successfully lobbied to legalize gambling and turned Hill Valley's dilapidated court house into a beautiful casino-hotel.

Biff birthday win was March 28th, 1958 and the picture when he is labeled the "Luckiest Man on Earth" is dated April 16th, 1959. So in about a year Biff has dominated the sports betting world, probably not enough time for the industry to react to his habits. By 1973 he had already been through three wives and finally married Lorraine. In the mean time he had started Biffco which had enough capital to build a nuclear power plant and operate a toxic waste disposal company. I would imagine this involved many investors/advisers as Biff isn't that bright.

biff's 21st birthday win newspaper

biff is the luckiest man on earth newspaper

What we can say for certain is that sometime between 1959 and 1973 Biff has become one of the most wealthy people in world. To add some reasonable speculation I would say in that 15 years either 1) the sports outcomes didn't change or 2) the outcomes did change and that is what causes Biff to form Biffco with the money he already had. Finally once 1979 rolls around and he opens the casino he is set for life and doesn't need to bet on sports any longer.

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    The comic series indicates that he'd occasionally bet on events in order to fund various failed ventures including a movie about 'Mad Dog' Tannen.
    – Valorum
    Oct 30, 2018 at 17:52
  • The sports almanac also has some useful information not directly related to who won a particular game/race. Knowing that a particular ball-player is very good can make you money (as a team owner, for example) even if his team loses a game that the almanac says he won.
    – Andrew
    Aug 20, 2023 at 20:37

im pretty sure the almanac would alter itself as events changed thus always keeping Biff in the green. Just like the photos and newspapers Doc and Marty used to keep track of outcomes, the statistics would change ...which leads me to wonder if Biff ever saw it change when we looked up stats.

  • 3
    Hi, welcome to the site. Note that your answer essentially repeats a point already made in ConMan's answer. If you're going to post an additional answer to a question that already has one or more answers, you should try and raise a new point, or at least post some new evidence to support a point already made. This answer doesn't really do either of those things. You might want to take the tour, to learn more about the site. Oct 3, 2021 at 17:54

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