Point Spread: The point spread remains the favorite way to wager on pro football, regardless of how many new forms of wagering come on stream. ItÂ’s called the line or spread and itÂ’s known as betting Â‘sides.Â’ The common misconception is that Las Vegas sets the spread as its best guess at the margin of victory. But really, it's a number they feel that is a perfect balance and will see an equal number of people to bet the underdog as on the favorite. A negative value like -6.5 means that team is favored by 6.5 points. So deduct 6.5 points from their total score. A positive value on the same game would be +6.5 (add 6.5 points to their final score) and would make that team an underdog of 6.5 points. The favorite must win by at least seven points to cover the spread. The underdog can lose by six points and still cover.