What is a Spread in betting?
Spread (also known as 'line' or 'handicap') is a figure set by the sportsbook to counter the perceived bias in abilities of opponents. By giving each team a points/goals/runs handicap, this creates a market in which the chances of success for both teams are deemed to be even. Think of this as if you are playing golf and certain players are given different handicaps to make the contest even (or as close to even as it can be) from the start. This is what a spread tries to achieve.
When a bettor is betting on the spread it is a bet on the margin of victory. Each outcome of a points spread bet has a handicap (or a line) attached to it. This is the way Sportsbooks level the playing field in the betting market giving both teams similar odds with a different handicap attached to the outcome.
Favorites & Underdogs
To understand how betting against the spread works you need to also understand the difference between favorites and underdogs. In betting the favorite is the team that is most likely to win the game as predicted by the sportsbook, while an underdog is the team that is less likely to win the game. When betting Against The Spread (ATS) the favorite would always have the handicap subtracted from their score while the underdog would have the handicap added to their score.
For example, if a game had a spread of 7, one team would have 7 points subtracted from their final score (the favorite), while the other would have 7 added to their final score (the underdog). The winner of the points spread is the team who covers the spread based on the handicap and the final score. That winner is also said to have “covered” the spread or won “ATS”
For example, say that the Kansas City Chiefs are 7-point favorites (-7) against the Tampa Bay Buccaneers.
If you bet on the Chiefs ATS you will need them to win the game by 8 points or more for you to win your bet. While if you bet on the Buccaneers ATS you will need them to either win the game or lose the game by 6 points or less for you to win your bet.
If the margin is exactly the same as the spread line e.g. the Chiefs win by 7 points (Buccaneers lost by 7 points) this is known as a push. This means you will get the money back from your original bet but you will not receive the profit.
Spread Betting in Baseball & Ice Hockey
In Baseball & Ice Hockey it is common for there not to be a Spread market, instead the preferred spread betting market is referred to as the Run Line for Baseball and Puck Line for Ice Hockey. These markets both work in the same way are similar to betting ATS. However, the difference is that Run Line & Puck Line are always set at 1.5, this means that no matter how one sided or close a game might be the favorite will always have a handicap of -1.5 subtracted from their score while the underdog will have +1.5 added to their score.