What is a point spread?

Point Spreads

The point spread (runline in baseball) is the handicap, or head start, that the linesmaker gives to the underdog. Betting against the spread can make a lopsided event more interesting - rather than just winning outright, the favourite must win by more than the point spread ("cover the spread") for bets on the favourite to win. The point spread’s purpose is to make betting on either side equally attractive.

Let's say the New England Patriots are at home against the Cleveland Browns in the NFL. All signs point to the Patriots being the favourite and the Browns the underdog. The linesmaker might decide to give the Browns a five-point head start, which is expressed as Browns +5, or Patriots -5. 

If you bet on the Patriots, you'll win your bet if they win the game by more than five points. If you bet on the Browns; however, you'll win your bet if they lose by less than five points (i.e., if their score is higher after you add five points to it).

The moneyline odds attached to the point spread determine your payout. A negative number (e.g., -170) shows how much money you must wager to win $100 while a positive number (e.g., +150) shows how much money you will win on a $100 wager. The standard odds of -110 may or may not be listed. Note that if one side is receiving a lot of action, the odds may be adjusted in an effort to balance the action.

You can place a point spread bet on the whole game or only a portion of it (when first half, second half, quarter, or 5th inning lines are offered). The point adjustment during the specified period of the game determines the betting outcome.