Because the spread is intended to create an equal number of wagers on either side, the implied probability is 50% for both sides of the wager. To profit, the bookmaker must pay one side (or both sides) less than this notional amount. In practice, spreads may be perceived as slightly favoring one side, and bookmakers often revise their odds to manage their event risk.
Let’s start with the basics: what do sports bettors mean when they talk about a ‘line?’ The word line, in the language of a sportsbook, can refer to either the odds and/or a point spread in any sports contest. Let’s take a look at an imaginary line the way you’d read it off the board sitting in a Vegas sports betting lounge or on the screen at your online book. Let’s imagine a game between the New York Giants and the Dallas Cowboys. Your book’s NFL betting line might look something like this:
In this example, we have a favorite to win, and an underdog. The Packers are the favorites, and that is shown by the (–) value in front of the 6. Underdogs are represented by the (+) value. The 6 point value is how many points either team could win, or lose by. If you think the Packers will win by MORE than 6 points, then you’d bet on the favorite in this case, meaning that the Packers have to win by 7 or more points in order for you to win your bet.