For every game, regardless of the sport, the oddsmakers first must decide which team is the favorite and which team is the underdog. Many factors go into the process. It’s not as simple as the team with the better record being the favorite. Things like home-field advantage and injuries can help the oddsmakers decide that one team is more likely to beat the other on any given day.
The favorite is considered the better team that is expected to win the game. Favorites typically have superior players, more experience, better coaching, a better track record of success and match up better against their opponents. The underdog, also known simply as the “dog,” is the worse team that is expected to lose the game. Underdogs don't match up well against their opponent. They might be less talented, less experienced and have inferior coaching.
However, because favorites are the better team and win the majority of their games, oddsmakers must make betting fair by providing pros and cons to betting favorites and underdogs. Otherwise, everyone would just bet always favorites and the sportsbooks would go bankrupt. As a result, oddsmakers level the playing field by creating risks for betting favorites and providing advantages for betting underdogs.
There are two basic ways to bet on a favorite or an underdog, which is referred to as betting “the side.” The most popular bet type is the point spread, also known as simply the spread or “SPD” for short. The spread is a certain number of points taken away from the favorite and given to the underdog in order to level the playing field. The spread has nothing to do with which team wins the game. The only thing that matters is the margin of victory.
The favorite “gives” or “lays” points to the underdog while the underdog “gets” or “receives” points. Favorites will have a minus sign (-) in front of their odds while the underdogs will have a plus sign ( + ) in front of their odds. If the two teams are even based on the oddsmakers projections and the game is considered a 50/50 game or coin flip, the spread is zero. This would be called a “pick’em” or just "pick" for short, with neither team laying or getting points.
The spread is available in almost all sports, but it is most popular in football and basketball because the margin of victory can be vast. Baseball and hockey also have the spread, but they aren't as popular because many games result in a margin of victory of one run or one goal. In baseball the spread is known as the "run-line" with the favorite giving 1.5 runs and the dog getting 1.5 runs. This means the favorite spread is -1.5 and the dog spread is + 1.5. In hockey, the spread is known as the "puck-line" with the favorite laying 1.5 goals and the dog getting 1.5 goals. If you bet either favorite, they would need to win by two or more runs or goals in order for you to win and cover your bet. If they only win by one, or lose the game straight up, you lose your bet. If you bet either dog, they would need to win the game straight up or lose by one run or one goal. Because underdogs are getting an extra run or goal and a half with the spread, bettors must pay a higher price on them. In turn, the price of betting a favorite on the spread is much cheaper because they have to win the game by more than one run or goal.
For favorites to win a spread bet, they need to win by any margin that is greater than the spread they are laying. For underdogs to win the spread bet, they need to win straight up or lose by a number less than the spread they are receiving. If the favorite or underdog fits this criteria, that is considered a “cover,” meaning they covered the spread and won the bet.
For example, let’s say the the New England Patriots are playing the New York Jets. The oddsmakers list the Patriots as 7-point favorites. This means the oddsmakers view the Patriots as 7 points better than the Jets. Bettors then have the choice of laying the 7 points with the Patriots, which would be referred to as betting the Patriots -7, or taking the points with the Jets, which would be referred to as betting the Jets + 7.
If you bet the Patriots -7, they would need to win by 8 points or more for you to win your bet and cover the spread. If the Patriots win by six points or fewer, or lose the game straight up, you lose your bet. If you bet the Jets + 7, they would need to either win the game straight up or lose the game by six points or less in order for you to win your bet and cover the spread. If the Patriots win by exactly 7 points that would be considered a “push,” in which case the sportsbooks would refund the money that you bet.
It’s important to remember that not all spreads are whole numbers. You often see spreads featuring half points. The extra half point is critical and could end up being the difference between a win, a loss and push. The extra half point is referred to as “the hook.”
For example, instead of the Patriots opening as 7-point favorites, the oddsmakers might instead set the line at Patriots -6.5. This means that if you wanted to bet the Patriots, they would need to win by 7 points or more for you to win and cover your bet. If you bet the Jets + 6.5, you would need the Jets to win the game or lose by six points or fewer. If they lose by exactly six points, you win and cover your bet because of the hook. With half-point spreads a game cannot end in a push.
In the betting world, teams are measured by two sets of win-loss records: their conventional win-loss record (straight up or "SU") and their win-loss based on how they perform when factoring in the spread, otherwise referred to as their “against the spread” or "ATS" record. This refers to how often a team covers, not how often they win. For example, the Jets might have a win-loss record of 7-9 but are 10-6 ATS. This means they've only won 7 of their 16 games, but have covered 10 of them. In terms of the standings, the Jets would be considered a losing team. But in terms of betting they would be considered a winning and profitable team to bet on.