With most other forms of sports betting, the wager is placed based on picking the winner. Someone would bet on the New York Giants beating the San Francisco 49ers, for instance. This is not the case with over/under betting. Instead, the actual winner of the game does not matter in the context of this kind of betting. Understanding over/under betting, which is also known as betting totals, is actually very straightforward, though the decision process can be much more complex than betting on moneylines or point spreads. That's because many other factors go into the setting of the total by oddsmakers and sportsbooks.

How Over/Under Betting Works

Rather than choosing a winner of a game or match, as would be the case with moneyline betting and point spread betting, over/under betting gets bettors to decide if the total score in a game will exceed the predicted total score by the oddsmaker. It doesn't matter which team wins. Let's take the hypothetical example of an NFL game between the San Diego Chargers and Dallas Cowboys. The Las Vegas sportsbooks may decide on a total score for the over/under betting of 43.5 points. This means that, at the end of the game, the oddsmakers believe that the combined score of San Diego and Dallas will be 43 or 44 points. To "take the over" means to wager that the total score for that game will be 44 points or more. The bet is that the actual total score will be "over" the predicted total score. To "take the under" means to wager that the total score for that game will be no more than 43 points. Continuing with this example, let's say that the hypothetical final score is 21-14. This is an actual total score of 35 (21+14). This is less than the over/under line of 43.5, so the "under" wager is deemed the winner. If the final score is 35-21, this is a point total of 46 (35+21). That is the over.

Payouts for Over/Under Wagers

Much like point spread betting, the payout system for over/under betting includes a commission for the sportsbook or whoever is accepting the wagers. The typical system would require a bettor to wager $110 to win $100. That $10 is the commission. While the price is typically -110, individual sportsbooks may offer slightly different payout schemes.

How Predicted Totals Are Determined

There are many factors that can go into the determination of a point total for a game for the purpose of over/under betting. In NFL football, two highly offensive-oriented teams will likely generate more points than two highly defensive-oriented teams. However, the matchups between the teams can also factor greatly into the determination of a total. The same can be said about NBA basketball. For MLB baseball, the starting pitchers can have a huge influence on the predicted total number of runs. This is because the top pitcher for a team may have a very low ERA and, thus, will likely allow very few runs. If the game has a starting pitcher that is fourth or fifth in the rotation, he is likely to have a higher ERA. As such, the number of total runs will likely be higher in that game.