Closing Line Value Calculator: The Math Behind CLV

What closing line value measures

Closing line value is the gap between the odds you bet and the market's last, best-informed price before the event starts. Positive CLV means you got a better number than the market settled on.

The close matters because it carries the most information. In a 2017 paper, researchers profited using closing odds across a 10-year historical simulation, then backed the same probability-based method with a 6-month minute-by-minute simulation and a 5-month stretch of real-money betting. The same authors describe bookmakers restricting successful clients, which is why sharp bettors treat CLV as the scoreboard rather than short-run profit: it shows up long before results do, and long before an account gets limited.

Step one: turn odds into implied probability

Implied probability is 1 divided by the decimal odds. Add both sides of a market together and the total runs past 100%. That overshoot is the margin.

Pinnacle's own two-way margin worked example uses prices of 1.926 and 2.020:

As Pinnacle puts it, the market percentage above 100% is the edge the book holds, here 1.43%. American odds follow the same idea: a plus price converts as 100 divided by (odds plus 100), so Data Golf's +254 sits at 28.2%.

Step two: remove the vig from both sides

Divide each side's implied probability by the market total. That is proportional de-vigging, and it is what most calculators do quietly.

Data Golf shows the two-way margin-free conversion plainly: 55% and 47% become 55/(55+47) = 53.9% and 46.1%. Run Pinnacle's market the same way and 51.92% becomes 51.19% (51.92 divided by 101.43), while 49.51% becomes 48.81%. Flip those back to decimal odds and the fair prices are 1.954 and 2.049.

The method extends to three-way markets. Data Golf's three-way Landry example starts from a 109.04% book (30.77% + 42.55% + 35.71%). Landry's 30.77% de-vigs to 28.2%, a fair price of 3.54, or +254 in American odds.

One caveat the calculators skip: proportional removal assumes the margin is spread evenly, yet books load more margin on longshots than on favourites, the favourite-longshot bias. The fair price on a big underdog is therefore an approximation, slightly generous to the longshot.

Step three: compare your price with the fair close

CLV as a percentage is your decimal odds divided by the fair closing decimal odds, minus 1. Written in probabilities it is the same thing: fair closing probability divided by your bet's implied probability, minus 1.

A hypothetical built on Pinnacle's numbers: you took side A at 2.020 earlier in the week, and it closed at 1.926 against 2.020 on the other side.

Skip the de-vig and the number flatters you by roughly a point and a half, because part of the drop from 2.020 to 1.926 was margin, not market movement. This is the same arithmetic Data Golf uses for expected value: treating one book's margin-free price as truth against another's offer gave an expected value of 5.75% on its Landry line. CLV just swaps in the de-vigged close as the truth.

Vig-free close or the sportsbook's close?

Use the vig-free close, and take it from the sharpest book you can. A soft book's closing price still carries its own margin and its own opinions, so comparing against it mixes your edge with theirs.

Pinnacle generally runs the lowest margin among the books Data Golf compared, with DraftKings and Bet365 higher. Pinnacle itself cites a 2.5% margin against up to 10% at some books in esports markets (as of October 2026). The lower the margin in the closing line, the less the de-vig step has to guess.

Closing line value calculator MLB

For baseball, run the calculation on the moneyline close. The moneyline is a clean two-way price, so both sides de-vig directly with the steps above.

The run line bundles a fixed spread with its price, and the spread's value moves with the total and the pitching matchup, so a run-line close is not a like-for-like benchmark for a moneyline bet. If you bet the moneyline, compare with the moneyline close; for pitcher-dependent markets, note that late lineup and starter news is exactly what the close prices in, which is why beating it is hard and why it is worth tracking.

Market questions

How to calculate closing line value?

Convert both sides of the closing market to implied probability, divide each by the total to remove the margin, turn the fair probability back into decimal odds, then divide your bet's decimal odds by that fair price and subtract 1. A positive result means you beat the close.

What is a good closing line value percentage?

Any positive figure against a de-vigged sharp close is a good sign, and the sign matters more than any single size. One bet proves little; what counts is whether your average stays above zero across a large sample, measured against a low-margin closing line rather than a soft book.

How to calculate a money line bet?

Decimal odds convert to implied probability as 1 divided by the odds. American plus prices convert as 100 divided by (odds plus 100), so +254 works out to 28.2%. Minus prices convert as the odds divided by (odds plus 100), both taken as positive numbers.

How to calculate the expected value of a bet?

Multiply the price you are offered (decimal) by your estimate of the true probability and subtract 1. Data Golf ran exactly this with one book's margin-free price as the truth and got 5.75% on its Landry example. CLV uses the same arithmetic with the de-vigged close as the truth.

Price and data sources

• Pinnacle, How to calculate betting margins, undated (accessed 2026-10-16)
• arXiv (Kaunitz, Zhong, Kreiner), Beating the bookies with their own numbers - and how the online sports betting market is rigged, 2017-11-11
• Data Golf, How sharp are bookmakers?, undated (accessed 2026-10-16)