That's because of the vig, or the amount the sportsbook charges for taking a bet. While receiving equal money isn't always possible, it's always the goal because if that's the case, the sportsbook will come out in the positive no matter the final result. And so, the sportsbook will continue to raise the line until the other side starts receiving action (from 10.5 to 11 to 11.5, etc). Sports betting odds are calculated with the main goal for sportsbooks being to receive equal money on both sides of a bet.įor example, if the Kansas City Chiefs are a -10 point favorite against the Oakland Raiders and are getting 90% of the money, the sportsbook would likely adjust their line so they don't finish in the negative if the Chiefs cover that spread.