The Spread

The most common types of sportsbook wagers focus on picking the winner of an individual or team contest. Because not all matchups feature objectively even teams, many contests include one side that is, by general consensus, more likely to win than the other side.

The uneven probability of potential outcomes that characterize most sporting events produces what are known as “favourites” and “underdogs.” Favourites are considered more likely to win, underdogs less. The relative probability of favourites and underdogs is reflected by the betting lines offered by sportsbooks. A $10 straight up bet on the favoured side will yield less profit than a $10 wager on the underdog.

Spread wagers account for uneven probability by handicapping the terms of victory from the bettor’s perspective. Rather than defining victory by choosing a winning side, spread odds allow bettors to wager on the margin of victory the favourite is likely to achieve. While this is theoretically more difficult than making a straight up bet, it boosts the success rate of underdogs and increases the payout for picking the favoured side.

An Example of a Spread Wager

Let’s look at an example of a standard spread betting option, using decimal betting odds.

 

Spread

Total

Money Line

New York Giants

(-7)

1.90

Over 44.0

1.90

Win

1.34

Cleveland Browns

(+7)

1.90

Under 44.0

1.90

Win

3.35

In this scenario, the New York Giants are favourites against the underdog Browns. The extent of the perceived advantage is quantified in the -7/+7 spread difference.

By choosing the Giants to win the spread bet, or “cover the spread,” they must win by more than seven points. If they win by six or fewer points, or lose the game outright, they have not covered the spread.

Conversely, a wager on the Browns to cover the spread will pay off only if they win the game, or lose by six or fewer points. In scenarios where the spread is a whole number, such as 7, spread bets may result in a tie. If the Giants win the above game by seven points, then all bets are refunded. Sometimes the spread will be a half number, like 6.5, which eliminates ties. But back to the example at hand.

Obviously, the Giants are more likely to satisfy the criteria of winning the game than they are of covering the spread. But notice that they pay 1.9x the wager to cover the spread as opposed to 1.34x to win the game.

From the underdog perspective, the spread pays less because the team can still lose while covering the spread. Thus, they pay more to win outright than to cover the spread.