Sports Betting 101: What is a Closing Line?

What is a Closing Line?

A bookmaker’s opening line is the bookmaker’s best estimation for the outcome of that specific event. Lines open at lower limits to help bookmakers get information with wagers, moving the number closer to true odds as they take more bets. As books get more money (information) from the market, they’ll increase the limits on wagers. Not all money is created equal, money from known sharps will move a number more than action from a square bettor or group. This is why the closing line matters — the line gets sharper and sharper (closer to the true probability) as the bets come in. The closing line is simply the odds on a game when betting closes, when the game goes off the board and the match begins. If a line opens at -2, closes -3, the closing line is -3. 

Now, you might be asking yourself, “Why do people care what a line closes at?” Well, one of the biggest indicators of future success in gambling is consistently beating the closing line and getting what is known as CLV.

What is CLV? 

CLV stands for closing line value and determines how much you beat the closing number by. If you beat the market (played a better number than the closing number), you get positive CLV, if the market moved against you and it closes worse than you played, you’ll have negative CLV. For example, let’s say you bet the Chiefs at -1 (-110) in the middle of the week and the line closes at -2 (-110), you beat the closing line by a full point, and your closing line value is over 4%.

This is an important tool to track your edge in a given market/sport. If you’re consistently beating the closing number, you clearly have an edge in that market. There are calculators available to calculate your CLV, but you can do it by subtracting the implied probability of the number you bet, from the implied probability of the closing number. Then you divide that sum by your implied probability and you’ll have your CLV.