Closing Line Value (CLV): What It Is and How to Calculate It

Closing line value (CLV) is how much better the price you took was than the price when betting closed. Take the over at +110, watch it close at -105, and you beat the close: the market ended up agreeing with you, and you got paid more than its final price for the same bet.

It matters because results are mostly luck for a long time. Over 500 bets at -110, chance alone swings your ROI by about 4 points either way, so a real 2% edge is invisible in your record. The closing price is the market's best estimate of the true chance, after all the sharp money has hit it. Beat it consistently and you are very likely a winning bettor long before your results can prove it.

There are two ways to put a number on it. The first is quick; the second is the honest one.

1. Price CLV. Turn both prices into decimal odds and divide: CLV = your decimal odds / closing decimal odds - 1. You took the over at +110 (2.10); it closed at -105 (1.952). 2.10 / 1.952 - 1 = +7.6%. That's how much more you'd be paid than someone betting the same thing at the close.

2. No-vig CLV, your expected edge. The closing price still has the book's margin in it. Take the vig out of the closing market and you get the market's fair chance; your edge is that chance times your decimal odds, minus 1.

The two numbers answer different questions. Price CLV (+7.6%) says how far the line moved your way. No-vig CLV (+2.7%) says what the bet was worth if the closing line is right, which is the figure to track. A bet can show positive price CLV and still be a losing bet at the fair price, when the move was smaller than the vig.

On spreads and totals the line moves in points as well as price. Take an NFL favorite at -2.5 and watch it close at -3.5 and you beat the close by a full point, and through the most common final margin in the sport, 3. A point through 3 or 7 in the NFL is worth far more than a point between 9 and 10, so don't count every half point as equal.

The clean way to compare is to look up what the closing market charges for your number. If the book would have charged -150 to buy the favorite down to -2.5 at the close, that's the closing price of your bet; run the sums above against it.

Every bet has some CLV, positive or negative, and a single bet's figure means nothing. What matters is the average over a few hundred bets and the share of bets that beat the close.

• An average no-vig CLV above 0 means you're beating the market's final price after the vig. At +1% to +3% you are doing what most professional bettors do.
• Beating the close more than half the time with a positive average is the pattern to look for; a few big moves carrying the average is luck in disguise.
• Negative CLV with a winning record usually means a lucky run. Expect it to fade.

Compare the noise: after 500 bets at -110, the ordinary swing in ROI from luck alone is about 4.3 points either way; after 1,000 bets it's still about 3. CLV settles much faster because every bet adds a measurement, win or lose.

The close is only a good estimate where the market is deep and sharp money can move it.

• Small markets. A player prop with a $250 limit at one book can close wherever that book left it. For props, take the close from the sharpest book you can see, or the consensus across several.
• Copied lines. Many books copy a few market makers; their closing number is a copy, not a test. Check the close at a book that takes big bets.
• Late news. A starter scratched an hour before the game moves the line for a reason you couldn't know. It still counts against you, but don't read one of those as a lesson.

The bigger lesson: if your bets keep landing on the wrong side of the close, the problem is the process, not the results. The guide to line shopping is the cheapest fix there is.

Our prop bet tracker works out CLV for every bet you log with the price you took and the closing price: the average, the share of bets beating the close, and a luck test on your record. It runs in your browser and nothing you type leaves the page.

The book that makes the case for judging yourself on the close, with data, is Joseph Buchdahl's Squares & Sharps, Suckers & Sharks.

Bet only where it's legal for you and only money you can afford to lose. If betting stops being fun, call or text the National Problem Gambling Helpline at 1-800-MY-RESET (1-800-697-3738), free and confidential.