How a betting line goes from a number to a market

Lines are set to balance action, not predict outcomes. Knowing how they form changes how you read them.

Most major sportsbooks open lines a few days before a game, sometimes earlier for marquee matchups. The opening line is set by a small team using a combination of power ratings, injury information, and recent form. Its primary goal is not to be the most accurate number possible -- it is to attract balanced action on both sides so the book profits from the vig regardless of outcome.