An Over/Under Bet is a wager that will only apply to a sports competition that involves scoring. For example you would not be able to place an Over/Under bet on a tennis match, auto racing, cycling, horse racing, or any other sport where it is a win or lose proposition that does not involve scoring. With a boxing match a Sports Book will have an Over/Under bet on the number of rounds that the match will go. Over/Under bets are very popular in Basketball, Baseball, Football, and Hockey.
Most Over/Under bets are about the combined total score of the game however there are some instances where an Over/Under Bet could be on the combined Total score of a half. Most players will make an Over/Under bet in addition to a win or lose bet. In Hockey there is a wager, which has been around for a very long time, which is called the Grand Salami. This is an Over/Under bet but it is on every Hockey team that is playing that day.
How does an Over/Under bet work?
Part of the betting line that is posted by a Sports Book is an Over/Under line. This is the betting line for the combined total score of both teams in the competition. For example if two basketball teams are playing there will be point spreads, possibly money lines, and an Over/Under bet. Say that the Over/Under bet is 198. If you bet on the Overs then you are wagering that the total score for both teams of the entire game will be 199 or more. If it is 197 or less you would lose your bet and if it was 198 then it would be a tie and there would be no action and all bets would be refunded. The Total Score is based upon the addition of what both teams in the contest score throughout the entire regulation and any overtime periods of the game. Over/Under bets are almost always paid off with 11/10 odds which means that you have to bet $110.00 to win $100.00.
How a Sports Book adjusts for unbalanced action
Because a Sports Book makes money on the 11/10 odds they would prefer if the distribution of bets was as even as possible between the two teams that are competing. If they experience heavy betting on one side over the other then they will usually not adjust the Over/Under betting line but will instead change the money line of the bet or the odds. So as an example, we take a boxing match were the line is 9.5 rounds. In this bet The Overs would win if the match went 10 rounds or more and the Unders would win if the match went 9 rounds or less. Because of the half of a round, there is no possibility of a tie on this wager. Now if the betting action was too heavy on the Overs of this match then the Sports Book would most likely change the money line or the odds. So the Overs bet would become something like 9.5 – 200. This would mean that if you bet the Overs, you would be risking $200.00 to win $100.00.