Over-Under Bet Definition

In sports betting, an over-under bet is a bet on whether a specific statistic for a game will be higher or lower than a pre-agreed value. This type of bet is also known as a total bet.

The most common type of over-under bet is on the combined score of two teams in a match. In this case, a bettor will wager that the total number of points scored in a game will be higher or lower than a set value (normally referred to as “the over-under” for that game). If they are correct, they will win. The bet is called a push if the actual number exactly equals the over-under, in which case all bets are refunded.

Key Takeaways

  • In sports betting, an over-under bet is a bet on whether a specific statistic for a game will be higher or lower than a quoted value. This type of bet is also known as a total bet.
  • The most common type of over-under bet is on the combined score of two teams in a match.
  • The payout on an over-under bet doesn’t just depend on predicting the score correctly. You should also pay attention to the odds (also called the vig or juice) so you know how much that sportsbook will take out of your winnings.
  • Gambling always involves a negative expected return—the house always has the advantage. 

What Is an Over-Under Bet?

Over-under bets go by several names. In the US, it’s common to see this type of bet referred to as a “total,” or abbreviated as O-U. All of these names refer to the same type of bet, though.

In an over-under bet, a sportsbook will predict a number for a given game. Most commonly, this is the total number of points that will be scored. Bettors will then wager that the actual number will be higher or lower than this prediction. With this type of bet, you are not trying to predict the actual score of a match. Instead, you might feel that there will be more points scored than the sportsbook is predicting, or fewer.

The best way to understand this is with a simple example. Let’s say the Bills–Chiefs total is 54. This is a high total for the National Football League (NFL), and you might think that the defensive strength of these teams will prevent that many points from being scored. You would therefore place an over-under bet that the score will be lower. Then:

  • If the Bills win 24-20 (44 points), you win
  • If the Chiefs win 34-24 (58 points), you lose

In the rare case that a score is exactly the same as the quoted value, the bet is called a push, and all over-under bets are refunded.

Though this bet is most commonly made with the combined score of the two teams, many other statistics can be used, including:

  • In American football, a player's or team's total rushing yards or attempts, down conversions (first or third), interceptions, completions, field goal percentage, etc.
  • In basketball, a player's or team's total assists, blocks, turnovers, steals, etc.
  • In baseball, a player's or team's total number of home runs, RBIs, etc.

Over-under bets are popular with people who are new to sports gambling because they work in a simple way. Over-under bets are among the most popular wagering options in sports betting,
behind point spreads and moneylines.

Over-under bets can be good for beginners, says Steven Petrella, deputy editor of The Action Network, a sports media company, and in some ways might be better than point spreads or moneylines because they're more intuitive. “All you need to decide is whether or not a game will go over or under a set number of points,” Petrella explains, and this “gives you a rooting interest in all aspects of the game.”

Important

Though over-under bets can relate to a wide variety of statistics, the most popular is the total points scored. If someone refers to “the over-under” in an NFL game, they’re likely referring to the total points scored.

Understanding Over-Under Bets

In order to understand how to use over-under bets, it’s instructive to see what they look like from the perspective of a sportsbook. The aim of a sportsbook is to have an equal number of bets on either side of the over-under for a given game. They will therefore post what they think is the most likely value for the over-under.

A lot of math goes into predicting the over-under for a given match, Petrella says, but there are two main factors: “pace (on offense) and efficiency (on both offense and defense).” And, like all odds in sports betting, these predictions will change as a betting pattern emerges. “After a few sportsbooks open up the first version of totals for a given sport on a given day,” Petrella says, “sharp bettors influence the lines with their betting action, and then other sportsbooks copy that number.”

Sportsbooks will also set the vigorish (or vig) for an over-under bet. This is normally set at 10%. Using American odds, this will result in both outcomes initially being quoted at -110 (which means that bettors must risk $110 to win $100). If the amount bet on both outcomes is exactly even, the money wagered by the losers will be paid to the winners, and the sportsbook will keep the 5% profit.
However, sometimes there may be an imbalance between the number of bets on over, and the number on under. In this case, the sportsbook will try to even out the numbers. They can use two strategies to do this:

  • Change the over-under value itself. If this was originally 45, and too many people have bet over, it might be adjusted to 46 to encourage others to take the under bet.
  • Change the odds. A sportsbook could lower the odds on the under to -105, for instance, and raise those on the over to -115. This will also encourage bettors to go with the under.

When it comes to paying out, a standard bet on a total is treated just like a point spread. The sportsbook will take its cut, and then pay out to the winners.

The payout on an over-under bet doesn’t just depend on predicting the score correctly. You should also pay attention to the odds (also called the vig or juice) so you know how much that sportsbook will take out of your winnings.

Over-Under Bet: An Example

Let’s take the fictional example of a Yankees–Red Sox game for which the over-under is initially set at 8 points, and the vigorish at 10%.

This means that you would be betting $1.10 for every $1 you want to win. And you’ll win if you correctly predict that the total points scored will be less or more than 8. This will be displayed as -110 odds. The same ratio holds for all bets, so if you bet $11, you’ll win $10. If you risk $55, you’ll win $50. $110 wins $100.

It can get a little more complicated. In low-scoring sports like hockey, soccer, and baseball, a sportsbook will often adjust the juice before moving the total number. Let’s say our Yankees–Red Sox game has a total of 8.5, but the sportsbook makes its projection closer to 9 than 8.

In that case, a sportsbook may make the over -120 and the under +100 to reflect its projection of how the game will go, forcing anyone who bets the over to risk a little bit more because that outcome is slightly more likely. At -120, you’re risking $1.2 for every $1 you want to win, and at +100, you’re risking $1 for every $1 you want to win. If the Red Sox win 5-3, under bettors win. If they win 6-3, over bettors win.

In 2018, the Supreme Court gave U.S. states permission to legalize sports betting if they wish to do so. It is still fully illegal in 17 states, including California, Massachusetts, and Texas. In four other states, there is some form of pending legislation.

What Happens if the Over-Under Is Exact?

If the over-under hits on the exact number, that's called a push. There is no winning bet, and all wagers are refunded to bettors no matter whether they took the over or the under.

Why Do Totals Change?

A sportsbook might change the total to keep the number of over and under bets even. But over-under values also vary historically. Just five years ago, for example, NBA betting totals in the 180s were common. But there has not been an NBA total under 190 since 2017. In the 2016-17 season, the average NBA total was just 210.6—almost 10 points less than the 2019-20 season.

How Are Totals Made?

There’s a lot that goes into making odds like totals, and it of course varies by sport. Bookmakers and bettors use many inputs—including how fast each team plays, offensive and defensive efficiency, weather, and more—to create a total.

The Bottom Line

Over-under bets, also called total bets, are a wager on whether a statistic from a game will be higher or lower than a quoted value. They are most commonly used in relation to the number of points scored in a sports match. Normally, you’ll be betting $1.10 for every $1 you want to win. And you’ll win if you correctly predict that the total points scored will be less or more than the prediction of a sportsbook.

As with all sports gambling, you should be careful when using over-under bets. As David Forman, the American Gambling Association’s senior director of research, puts it: “What’s most important is that every bettor takes the time to learn the odd and rules of their wagers and only bet within their budget. Sports betting should be enjoyed purely for fun, not as a money-making opportunity.” And that applies to over-under bets as much as to any other type.

If you or someone you know has a gambling problem, call the National Problem Gambling Helpline at 1-800-522-4700, or visit ncpgambling.org/chat to chat with a helpline specialist.

Article Sources

Investopedia requires writers to use primary sources to support their work. These include white papers, government data, original reporting, and interviews with industry experts. We also reference original research from other reputable publishers where appropriate. You can learn more about the standards we follow in producing accurate, unbiased content in our editorial policy.
  1. Gambling Sites. “Different Types of Bets Explained.”

  2. The Action Network. “Over/Under Definition, Examples.”

  3. Gambling Sites. “Total Bets and Over/Under Bets – Everything You Need To Know.”

  4. American Gaming Association. "Interactive Map: Sports Betting in the U.S."

  5. Bookies.com. “Understanding Over/under Betting For Sports Bettors.”

  6. American Psychiatric Association. "What is Gambling Disorder?"

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