What is ATS?
ATS refers to Against the Spread. This is a team's record compared to the line / spread. If a team wins against the line, clearing the spread, this means they won ATS or ‘covered’ the spread. If a team has a strong ATS record this means they have outperformed Sportsbooks’ expectations.
When a bettor is betting ATS, 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 least likely to win the game. When betting 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 the spread was set to 7 for a given game, one team will 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.
To demonstrate this, say that the Kansas City Chiefs are 7-point favorites (-7) against the Tampa Bay Buccaneers (+7).
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 markets are referred to as the Run Line for Baseball, and Puck Line for Ice Hockey. These markets both work in the same way and are similar to betting ATS. However the difference is that the 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. This also means that unlike the Spread markets for other sports, where the odds will generally be identical or similar, Run and Puck Lines can be substantially different depending on how heavy the favorite is.