Jimmy Boyd in Most bettors judge themselves by whether last week was a winning week. That tells you almost nothing, since a handful of good or bad results can happen to anyone regardless of skill, and it takes a huge sample before win-loss record separates luck from edge.
This calculator takes the odds you bet and the closing odds on the same side, then tells you your closing line value as a percentage. Beat the close consistently and you’re finding value before the market catches up to it, which is the clearest sign you actually have an edge.
Logging Your Number Against the Closing Line
Start with the price you actually bet, entered as American odds, positive or negative. Next enter the closing odds on that same side, the number the market settled on right before the game went off. If you want the sharpest read, add the closing odds on the other side too. That lets the calculator strip out the vig and land on a true no-vig probability instead of just the raw implied number.
Once you run it, look at the closing line value percentage first. That’s the headline number, how much better your price was than the fair closing line. Below it you’ll see your implied probability, the closing implied probability, and the expected return per dollar at the closing probability, which turns the percentage into real cash terms.
From +105 and -110 to 7.38% of Value
The formula is simple once you see it. Take the decimal odds of the bet you made, multiply by the closing line’s probability, and subtract 1. If you only enter one closing price, that probability is just the implied probability baked into that number, vig included. Enter both sides and the calculator removes the vig first, landing on a true no-vig probability that’s a cleaner read on what the market actually thinks.
Take the example on this page. You bet +105, which is 2.05 in decimal odds and carries an implied probability of 48.8%. The line closed at -110 on your side with no opposite price entered, so the closing probability used is -110’s implied probability, 52.4%. Multiply 2.05 by 0.5238 and you get 1.0738. Subtract 1 and you land on 7.38%, the closing line value. Expected return per $1 at the closing probability comes out to $0.07, small next to your stake but exactly the edge the math found.
Deciding Whether Your Price Beat the Market
Closing line value matters most when you’re trying to figure out whether you actually have an edge, not just a good week. A win-loss record needs a massive sample before it separates skill from luck. CLV doesn’t. Every bet gets graded against the close, win or lose, so you can track it in real time long before your bankroll would tell you anything useful.
The common mistake is betting the same number the market ends up closing at, then acting surprised when a stretch of bets nets out flat. If your price never beats the close, you’re not finding value, you’re just matching the market’s final read, and the vig eats the rest. Betting early, shopping multiple books, and getting a number before news or sharp money moves it are the real ways to generate positive CLV.
A sharp bettor tracks this number across every bet, not just the winners, and looks for a positive average over time. One bet with strong CLV can still lose. A large sample of bets with positive CLV almost never loses money in the long run, which is the whole point of measuring it instead of just counting wins.
Questions About Beating the Closing Line
Is 7.38% closing line value good or just an example? It’s the result from the worked example on this page, using +105 against a -110 close. Any positive CLV means you beat the fair closing price. The bigger the number, the more room there was between what you got and where the market settled.
Why enter the other side’s closing odds if it’s optional? Without it, the closing probability is just the implied probability of one price, vig included. Adding the other side lets the calculator solve for the no-vig fair probability, so your comparison isn’t skewed by the book’s cut.
Can you have positive CLV and still lose the bet? Yes. CLV measures whether your price beat the market, not whether the bet won. Over enough bets, positive CLV lines up with profit even though any single result can go either way.
Does closing line value work the same for every sport? The math doesn’t change. Enter the odds you took and the closing odds on the same side, and the other side too if you have it, and the calculator handles the rest regardless of what’s being bet.
