The over/under (O/U) bet is terminology describing a wager in which a bookmaker will predict a number for a statistic in a particular sporting event. In most cases this will relate to the number of points or goals scored.
A bet is placed on whether or not the actual number in the match will be higher or lower than that number.
O/U betting depends on the sport so it’s easier to look at each one individually.
Football Over/Under Betting
The O/U for Super Bowl LII was 47.5 points. The typical O/U betting line would have looked like this:
47.5 OVER -110
47.5 UNDER +110
The final score ended Philadelphia Eagles 41-33 New England Patriots, meaning that there were 74 points scored.
If you had placed a bet that over 47.5 points would be scored, you would have won the bet.
O/U bets are also sometimes referred to as ‘Totals’. It relates to the combined final score of the match.
Here is a screenshot from Bet365 of what current football over/under bets look like:
There will be instances in O/U betting where bookmakers make the line with a whole number. If the final score or total number of points equals this number, the bet ties and pushes.
So, using the above screenshot as an example, notice the Packers @ Lions match has the betting lines at O/U 51 points.
If there are 52 points or more scored, the over bet would win. If there are less than 51 points scored, the under bet would win.
However, if there are 51 points scored exactly at the end of the match, the bet pushes.
In the event of a push, no matter if a bet was placed on the over or under, the original bet gets refunded.
If a game enters overtime, the bet remains in play. An O/U bet acts in the same way as a moneyline bet as it covers the entire match, including regular and overtime.
For obvious reasons, if the match goes into overtime and you’ve bet on the under, you’re not enjoying the situation as much as someone who’s bet on the over.
NHL Over/Under Betting
Typically in the NHL, hockey over/under betting is based on the total number of goals scored in a match. The line is usually set at O/U 5.5 goals.
To win an over bet, there must be 6 or more goals scored. To win an under bet, there must be 5 or fewer goals scored.
In the case of whole numbered hockey betting lines, it will be set to 6 goals. Over 6 goals scored wins the over bet, under 6 goals scored wins the under bet and 6 goals scored exactly results in a push.
Here is a screenshot of what the NHL betting lines tend to look like:
Baseball Over/Under Betting
In baseball, the O/U bets are based on the number of runs made in the match.
Where ice hockey O/U goals scored lines tend to be standardized to O/U 5.5, baseball over/under lines vary on the match ups.
As an example, Milwaukee Brewers @ Colorado Rockies has O/U lines of:
Over 9.5 -105
Under 9.5 -115
For the over bet to win, there must be more than 10 runs scored. For the under bet to win, there must be 9 or less runs scored.
In the event of lines set at, for example, O/U 10.0, the over bet wins if 11 runs or more are scored, the under bet wins if less than 10 runs are scored and the bet pushes if exactly 10 runs are scored.
Here is a screenshot of O/U lines for upcoming matches:
Basketball Over/Under Betting
Basketball over/under betting is based on the number of points scored rather than the number of baskets.
You will likely see the the line as something like this, using Golden State Warriors v Cleveland Cavaliers Game 1 NBA Finals as an example:
Over 217.5 -120
Under 217.5 -120
So, in order to win the over bet, there must be 218 or more combined total points scored. To win the under bet, there must be 217 or less combined total points scored.
Some bookmakers may have placed the NBA over/under betting line at 218. This would have resulted in over bets winning if 219 points or more were scored, under bets winning if less than 218 points were scored and a push if exactly 218 points were scored.
Similar to the NHL, if NBA games go into overtime, the O/U bets remain in play. However, for Euro Basket games, some bookies may not count OT.
Soccer Over/Under Betting
For soccer matches, the main O/U bets are on the total number of goals scored.
The line is usually set at 2.5 goals per match.
So, to win the over bet, there must be 3 or more goals scored and to win the under bet, there must be 2 or less goals scored.
The lines will look like this example of the Manchester United v Newcastle United match:
Cricket Over/Under Betting
O/U bets can be placed on the total number of runs made in a match.
For test matches, the number of runs expected will be higher than Twenty20 or ODI matches due to the extended length, so the betting lines will adjust depending on the game variant.
For example, the O/U line for an upcoming Twenty20 match has been set at:
Over 310.5 -120
Under 310.5 -120
For the over bet to win, there must be 311 or more runs scored. For the under bet to win, there must be 310 or less runs scored.