To understand “Against the Spread” (ATS) we need to first understand “Spread Betting”. Spread betting is a modern construct. It was invented in North America by a math teacher to make wagering on the weaker team in games with a huge favorite.

The most simple way to think of it, is the weaker team is given additional points before the game starts. Likewise, a bet on the stronger team starts out “minus” points. Spread betting is the main odd offered for high scoring sports like NFL, NCAAF football and NBA, NCAAB basketball. Sometimes spreads are given in other low scoring points but these are a special kind of odd specific to a sport. We’ll cover “runline” and “puckline” in another post. The reason low scores are ignored is that adding a single point, or even half-point to the score of a hockey or baseball game could shift the odds wildly.

Here is an NFL example featuring some real odds for an upcoming game:

Spread | Odds | Payout on $100 | |

Carolina | -3 | +100 | $100.00 |

Denver | +3 | -120 | $83.33 |

Here Carolina is indicated as the favorite because their spread is -3. Denver’s spread is +3. What that means is that if you bet on Carolina, you need to subtract 3 points from Carolina’s final score then evaluate if you won the bet. Similarly, a bet on Denver means you take the final score and add 3 points to Denver’s score and determine if Denver wins.

Before placing the bet it is vital that you also take the odds into account. In the above example an $100 bet on Carolina pays $100. A $100 bet on Denver only pays $83.33. Completing that math is very important since a bet on Denver adds points, but does eliminate some of your return on investment. Always take odds into account. People frequently ignore this step because the odds in spread betting are frequently -110/-110.

Below is a possible score:

Final Score | Spread Score | ||

Carolina ← Your Bet | 21 | 21-3= 18 | ← Spread Winner |

Denver | 17 | 17 |

Here your bet on Carolina at -3 points means that at the end of the game you need to subtract 3 points to determine the spread winner. In this case the winner is still Carolina with a score of 18-17. An important point here: with this bet you can say that you won this bet “Against the Spread”, meaning you had the favorite and they covered the spread, or deficit given to the favorite.

Below is another example where you place a bet on Denver:

Final Score | Spread Score | ||

Carolina | 14 | 14 | |

Denver ← Your Bet | 12 | 12+3=15 | ← Spread Winner |

Here Carolina does win the game but when we go to determine the spread winner. Adding the 3 points to Denver makes them the spread winner, and you would win your Denver bet. Some people incorrectly call this an “Against the Spread” win, but strictly speaking, it is not.

Another important item to keep in mind is a “Push” in spread betting. A push happens when the spread is applied and you end up with a tie game, as below:

Spread | Score | Spread Score | |

Carolina | -3 | 14 | 14 |

Denver ← Your Bet | +3 | 11 | 14 |

A push is generally not ideal for anyone. For the sportsbook, a push means they make no profit and return all money to bettors. For you, it means that you have tied up money in a bet that could have been earning you money in another bet. I will cover that in another article about the opportunity cost of pushes.

This outcome is where half-points become important. Sportsbooks generally like half points since there is a guaranteed outcome and they generally don’t care which side wins. Here is our above example, only there is an extra half point added to the spread:

Spread | Score | Spread Score | |

Carolina | -3.5 | 14 | 14 |

Denver ← Your Bet | +3.5 | 11 | 14.5 |

These half points can be tough to understand at first but once you get the hang of them they are easy. What isn’t so easy is assigning a value of the half point, since the above outcome means Carolina must win by more than a field goal.

Spread betting is exactly the same in basketball and other high scoring sports. To sum up, a spread is an amount of points you add or subtract from one team’s score to determine the winner. Betting on the favorite and winning is called winning against the spread. Finally, watch out for half points, as they both mean there is a result, but that result might not always be in your favor.