What is the Over/Under in Sports Betting?

Patrick Lynch
By Patrick Lynch
Sports & Casino Expert
Updated Jan 6, 2023
Read time 8 min

The over/under betting line is one of the most popular betting markets, attracting huge interest and sums of money. One of the main reasons why bettors gravitate towards this market is its apparent simplicity. You must predict whether a certain match statistic will be higher or lower than the line set by the bookmaker.

It is a lucrative market for the bookie because of its popularity and the substantial edge they take on every wager. However, with knowledge of how over/under betting works, you can simplify your strategy and make money.

This article further explains over/under betting with examples, outlines why the line moves, and provides tips on how to win.

What Does Over/Under Mean in Betting?

The over/under line is a simple wager where you must predict whether a sporting event will have over or under the line set by the bookmaker. It is considered one of the three main betting markets, along with Moneyline and spread betting. You can learn more about wagering on the handicap in our spread betting guide. The nature of the line depends on the sport; it consists of points in the NFL and basketball, runs in baseball, and goals in soccer and ice hockey.

The most common market is the combined number of goals/points/runs in a game, although there are also prop bets on teams and players.

There are bets in whole numbers and wagers with .5 on them. The whole numbers allow for a push bet, which means you get your money back. Let’s explore over and under betting in action with three examples from different sports.

How Does Over/Under Betting Work?

There are often dozens of over/under betting markets for any event, with more added once the game commences. Keep reading for quick and easy examples of what to expect.

Example #1

In an NBA matchup between the Boston Celtics and the Oklahoma City Thunder, the over/under betting line is set at 235.5. The Celtics are a strong favorite, but you believe the Thunder have a good enough offense for the game to result in a high-scoring affair. Therefore, you back the over side of the equation at odds of 1.90.

In this scenario, you need the game to have 236 points or more to win your wager. Therefore, if the Celtics win 134-114, the total of 248 points is easily enough to cover your bet. However, if the Celtics triumph 118-107, the 225-point total means you lose.

Example #2

In the NHL, the Montreal Canadiens play the Nashville Predators. In this instance, the puck line is 6.0 goals. Here we have a  situation with the possibility of a ‘push’ occurring. This will happen if there are exactly six goals in the game. In these circumstances, you get your stake back, as the bet neither wins nor loses.

If you back the ‘under’ side of the line, you need the game to have a maximum of five goals to win. Should the game finish 4-3 to the Predators, for example, the seven-goal total means you lose your wager.

Example #3

The Miami Dolphins play the New York Jets in the NFL, with the over/under betting line set at 38.5 points. Therefore, a bet on overs only wins if the match has 39+ points. A wager on unders is only successful if the game has a maximum of 38 points. Therefore, if the Dolphins win 24-20, betting on the overs line was the right call.

Please note that over/ under betting may not include points scored in overtime. Suppose the Dolphins-Jets game finishes 18-18 in regulation and 24-18 after overtime. In this case, a bet on over 38.5 points could lose because only 36 points were scored in the first four quarters. It depends on the crypto-betting site’s terms and conditions, which we advise you to check before placing a wager.

What Causes Over/Under Betting Values to Change?

The O/U line varies drastically depending on the sport. Basketball and American football, for instance, are higher-scoring sports than soccer, baseball, and ice hockey. An over/under betting line of more than 220 points in an NBA basketball game is normal.

In contrast, most soccer games in professional leagues have the line set at 2.5 or 3.5 goals. In the MLB, a run line of 6.5 is deemed low, with 9.5 on the high end.

As for why over/under betting lines change, many factors are at play. Bookmakers must account for different things, including the respective strengths of each team’s offense and defense and the likelihood of their styles merging for a high- or low-scoring game.

After the betting site sets the odds, the action moves depending on what bettors do. The bookie must move the line to reduce its liability. For instance, if bettors wager a significant sum on the Celtics versus Thunder game having over 235.5 points, the bookmaker may adjust it upwards to 237.5 to encourage bettors to choose the under side of the line.

Another option for a crypto sportsbook is to reduce the odds on a line if a lot of money is placed on it. For example, the 1.90 odds for the Celtics/Thunder 235.5 over line could become 1.8, while the odds on ‘unders’ may increase to 2.00 from 1.90.

Over/Under Betting Lines Change With the Times

Over the years, certain sports have become higher or lower scoring, which has changed the line. For example, NBA games are higher scoring now than they were a few years ago. This is seemingly due to increased offensive efficiency, with the emphasis no longer on defense. Data published in The Athleticrevealed that the number of players scoring 20+ points in a game has almost quadrupled compared to the 2012-13 season.

The pace of NBA games is also quicker than a decade ago, which means more shots. Even if offensive efficiency hadn’t increased, matches would have higher scores.

Ultimately, bookmakers have responded by increasing the over/under betting line to reflect this relatively new trend.

When choosing a sportsbook, it makes sense to line shop. This will give you the best prices. Part of this process involves calculating the bookie edge.

Calculating the Crypto Betting Site’s Edge

It is easy to calculate the site’s edge. Divide the decimal odds by 100 and add the totals of the two markets. The total will be over 100, signifying the bookmaker’s edge. A total of 107 means an edge of 7%, for instance. Incidentally, if the total is under 100, you have an edge on the market or the opportunity for an arbitrage bet. However, such opportunities are rare.

Using our Celtics versus Thunder example again, the odds for both over and under are 1.90.

100 / 1.9 = 52.63

52.63 + 52.63 = 105.26

In this instance, the bookmaker enjoys a healthy 5.26% edge. Does this mean that you can’t profit from over/under betting? No! It is challenging, but with the right research and laser-like precision in your wagers, you can come out on top.

Over/Under Betting – How To Win

First and foremost, know the site’s rules! The terms and conditions may change from one site to the next. As we outlined earlier when discussing overtime games, failing to check the crypto betting site’s Ts and Cs could cost you dearly. Now, let’s look at ways to get the most out of over and under betting.

Account for Relevant Factors

It is a mistake to take a total points line at face value. You must consider the most relevant factors, which can vary from one sport to the next. For instance, the weather plays a big role in NFL over/under lines. If the Green Bay Packers play the Detroit Lions at Lambeau Field in the snow, you can expect a fairly low points total.

In contrast, since NBA games take place indoors, the weather is of no consequence. However, basketball is a game of tempo, and in the modern era, a match with two high-tempo teams will likely result in a high-scoring affair.

In the MLB, if the game takes place on a windy day, the total number of runs scored will likely be high. However, having a left-handed pitcher throwing to a team with several left-handed batters may decrease the final run total.

Use Low Liquidity to Your Advantage

This primarily relates to betting exchanges, although the over/under line generally won’t move much in markets where little money is wagered.

If you use a betting exchange, note the pricing gap when there is low liquidity, as this is a good indicator of true odds. Next, look at the over/under line at a crypto sportsbook to see if there is value.

For example, an NBA game between the Sacramento Kings and the Utah Jazz might have minimal liquidity two days before the event begins. At that time, you see that the over 242.5 points market is offering odds of 1.89, but there’s a big gap in the available ‘lay’ odds (the equivalent of betting on under 242.5 points) on over 242.5 points, which are at 2.22.

This suggests that the ‘true’ odds of over 242.5 points lie between 1.89 and 2.22; the midway point is about 2.05 or 2.06.

Next, you visit a crypto betting site and find that the odds on over 242.5 points in the game are 1.90. This suggests that you’re not getting value. Indeed, you’re arguably better served looking into the under side of the line.

Consider Cashing Out

When betting on low-scoring sports, it is worth backing unders with a view to cashing out or laying off the bet with time decay, causing rapid price movements.

For instance, in a soccer match with a standard total set at over/under 2.5 goals, you could bet on the ‘under’ part of the line if you believe a slow start is likely. This is a common tactic used by traders on betting exchanges. If there are no goals in the first half, you can cash out for a profit or hedge, which will allow you to remove your liability, effectively giving yourself a free bet.

If the first half has one goal, you’ll have the chance to remove most of your liability or allow the wager to run. Of course, an early goal places you in a weak position, so use this tactic sparingly!

Over/Under Bets Are a Solid Place To Start Your Journey

O/U bets are good options for relative novices or individuals looking for simpler bets. Bookmakers have recently increased the number of over/under betting markets. Now, you can bet on match points, team points, and player scores, among other things. The wide availability of in-play markets offers additional opportunities and extra excitement, particularly in fast-paced sports like basketball, where teams score frequently.  

The over/under betting market is often a binary choice (barring occasions where a push bet is possible), but don’t assume that a lack of complexity means it is easier to win! You still need to conduct a lot of research to gain an edge on the bookmaker. After all, these sites benefit from sophisticated technology that tells them what constitutes a fair line. Then, they spin things in their favor with the house edge.

From your side, it is best to specialize in a sport and a specific market. For example, you might stick with the total points market in NBA games. Remember to line shop and take into account the wide variety of factors that affect the scoring capacity of a team or individual.

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Patrick Lynch
Patrick Lynch
Sports & Casino Expert

Patrick has been a professional writer since 2009. He knows the issues players face when trying to find reputable casinos and performs forensic analysis on every site he reviews. Since joining in 2021, Patrick has had his eyes opened by the potential of the cryptocurrency market. With a background in sports betting, he realizes the possibilities afforded to successful bettors when using digital currency.