Closing line value explained: what it measures, how to calculate it, and why the final price is the benchmark
Most people judge a bet by whether it won. That is the least informative thing about it. A single wager at even money is a coin flip with a small tilt at best, and it takes hundreds of results before luck stops dominating a record. Closing line value asks a different question: when the market had absorbed all the information it was going to get, team news, injury reports, weather, the money of the sharpest bettors, was your price better or worse than where the market settled? That question can be answered for every bet, the day it is placed, and it is the measure professional bettors and the bookmakers who price against them use to tell skill from luck.
What the closing line is
The closing line is the last price a market offers before betting stops, usually at the start of the event. For a point spread it is the final number and price; for a moneyline it is the final odds on each side; for a Kalshi or Polymarket contract it is the last traded price or midpoint before the game, election or data release. It matters because it is the price that has seen the most information and, on a major market, the most money. Early lines are set by a bookmaker's model with low limits. As limits rise towards the start, bettors with good information or models bet into any mistakes, and the bookmaker moves the price after each bet it does not like. By the close, the obvious errors have been bet out.
Not every close is equally good. The benchmark most analysts use is the close at a high-limit, low-margin bookmaker or a deep exchange, because a price that accepts large bets and still does not move has been tested. A closing line at a book with low limits and a wide margin is a weaker yardstick, and a close on a lightly traded prediction market contract can be moved by a single order.
How to calculate closing line value
There are two common ways to express CLV, and they answer slightly different questions.
| Method | Formula | What it tells you |
|---|---|---|
| Raw price change | Your decimal odds ÷ closing decimal odds − 1 | How much the price moved after you bet. Includes the bookmaker's margin, so it overstates the edge. |
| Against the no-vig close | Your decimal odds × fair closing probability − 1 | The estimated expected value of the bet, if the close is an accurate probability. |
| Margin-factor shortcut | Your decimal odds ÷ closing decimal odds ÷ (1 + margin) − 1 | A quick approximation of the second method, used by analyst Joseph Buchdahl. |
| Prediction markets | Closing price − your price − fee, in cents per contract | The expected profit per contract if the closing price is the fair probability. |
The second method is the one that estimates edge. To get the fair probability, convert every side of the closing market to an implied probability (1 ÷ decimal odds), add them up, and divide each by the total. The total is above 100% by the bookmaker's margin, the overround; dividing it out spreads the margin proportionally across the sides. Our implied probability converter does this for two to four outcomes, and the guide to the vig explains the margin itself.
A worked example
On Tuesday you bet an underdog at +150, decimal 2.50. By kickoff the same side is +120 (decimal 2.20) and the favourite is −140 (decimal 1.714). The market moved towards your side.
| Step | Calculation | Result |
|---|---|---|
| Implied probability, your side at the close | 1 ÷ 2.20 | 45.45% |
| Implied probability, other side at the close | 1 ÷ 1.714 | 58.33% |
| Overround | 45.45% + 58.33% | 103.79% |
| Fair probability, your side | 45.45% ÷ 1.0379 | 43.80% (fair odds 2.283, about +128) |
| Raw price change | 2.50 ÷ 2.20 − 1 | +13.6% |
| CLV against the no-vig close | 2.50 × 0.4380 − 1 | +9.5% |
The raw change, +13.6%, flatters the bet because it compares your price with a closing price that still contains the bookmaker's 3.8% margin. Against the fair close, the bet is worth about 9.5 cents per dollar staked. It can still lose; the market's fair probability for your side is under 44%. What CLV says is that if you could place this bet many times at this price, you would expect to come out ahead.
The same logic works on an exchange. Buy 100 Yes contracts on Kalshi at 42 cents as a taker: the stake is $42.00 and the fee is 0.07 × 100 × 0.42 × 0.58 = $1.71 after rounding up, so the outlay is $43.71. If the contract trades at 50 cents when the event starts, the position is worth $50.00 at the closing price, an expected gain of $6.29 or 14.4% on the outlay, before any fee to exit. Had it closed at 45 cents, the expected gain would be $1.29, and the fee would have eaten most of the move. Our fee calculator prices that part.
Why the close is treated as the benchmark
The case for CLV rests on one empirical claim: that closing prices at efficient books are close to true probabilities. Buchdahl tested it on four seasons of Pinnacle football odds from 2012/13, taking the home, draw and away prices for each match, 87,960 pairs of earlier and closing odds in all. He treated the ratio of the earlier price to the closing price as the expected value of a bet at the earlier price, then plotted that expectation against the yield actually achieved at level stakes. The slope was almost exactly 1.00: bets that beat the close by a given margin returned close to that margin. Expected yields ran a few percent above realised ones, a gap he put down to the margin, which he had not removed in that test.
The practical consequence is speed. A record of results needs hundreds or thousands of bets before it says anything reliable about skill. A record of prices against the close says something much sooner, because every bet contributes a measurable number instead of a win or a loss. In another analysis, Buchdahl looked at a tipster whose 26 tips had shortened 23 times and lengthened 3 times by the close, an average of about 10% better than the closing price. The odds of that pattern happening by chance were about 1 in 100,000, and after the margin it implied a long-term yield of roughly 6% to 7%, a conclusion drawn from two months of tips rather than two years of results.
| Your odds | Closing odds | Margin | Estimated edge (shortcut) |
|---|---|---|---|
| 2.30 | 2.00 | 3% | +11.7% |
| 2.10 | 2.00 | 3% | +1.9% |
| 2.00 | 2.00 | 3% | −2.9% |
| 1.95 | 2.00 | 3% | −5.3% |
The third row is the default for anyone who bets at the closing price: the expected loss is the margin. That is why the usual verdict on a bettor who never beats the close is that they are paying the vig on every bet, whatever their recent results.
Where CLV misleads
CLV is only as good as the closing price behind it. Four situations weaken it.
- Thin markets. In a lower-league match, a player prop or a prediction market contract with little volume, the close may reflect a handful of orders. Beating it proves less, and a single large bet, including your own, can move it.
- The wrong close. Comparing a bet with the close at the same soft book can mislead if that book was slow to move. Analysts usually measure against the sharpest available close, or an average of several.
- Margin left in. The raw price change always looks better than the edge. On a two-way market with a 4% to 5% margin, a bet can beat the raw close by a couple of percent and still have negative expected value.
- Small samples and selection. Ten bets that beat the close is not a skill. Records that publish only some bets, or settle on prices nobody could actually get, fail the test in a different way: Buchdahl found one advertised record where the tips drifted against the close on average, which is hard to square with the yield claimed.
What this guide does not cover
This guide explains a measurement. It does not cover how to find bets that beat the close, staking methods, the rules that individual sportsbooks or exchanges apply to winning customers, or the tax treatment of winnings. Whether sports betting or event contracts are legal where you are depends on your state; our Kalshi legality tracker covers prediction markets state by state. Figures in the worked examples are illustrations, and the empirical findings cited are from football markets and published analyses, as of November 2026.
Frequently asked questions
What is closing line value?
Closing line value (CLV) is the difference between the odds or price you got and the final price before the event started. If you took +150 and the same side closed at +120, you beat the closing line. Measured against the closing price with the bookmaker's margin removed, it estimates the edge of the bet.
How do you calculate closing line value?
Convert both prices to decimal odds, remove the margin from the closing market to get a fair probability, then multiply your decimal odds by that fair probability and subtract 1. A bet at 2.50 on a side with a no-vig closing probability of 43.8% has an estimated edge of 2.50 × 0.438 − 1, about +9.5%.
Does beating the closing line guarantee a profit?
No. CLV estimates expected value; single results still vary widely. It is only as good as the closing price it is measured against, and in thin markets the close can be wrong. Over a large sample, bettors who consistently beat an efficient close should expect returns close to their average CLV.
Does closing line value apply to Kalshi and Polymarket?
Yes, in the same way. A contract bought at 42 cents that trades at 50 cents when the event starts was bought below the final price. Fees count against the edge, and the closing price on a thin contract is a weaker benchmark than the close on a heavily traded sportsbook market.
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- Implied probability converter: odds and cents to no-vig probability
- Expected value explained: the one number behind every bet
- What is the vig? How sportsbook margin works
- How bookmakers set odds: power ratings, vig and line movement
- Odds converter: American, decimal, fractional and implied probability
- Is Kalshi legal in your state? The 50-state tracker
Sources
- Joseph Buchdahl, Football-Data, The Efficiency of the Pinnacle.com Closing Line, for the 87,960 price pairs, the slope of about 1.00 and the margin gap.
- Joseph Buchdahl, Football-Data, Using the Closing Betting Odds to test for a Tipster's Skill, for the margin-factor formula and the tipster examples.
- Pinnacle Betting Resources, What is Closing Line Value (CLV) in Sports Betting?
- Pinnacle Betting Resources, Efficient Market Hypothesis in Sports Betting.
- Kalshi, Fee schedule, for the taker fee formula in the exchange example. Worked-example figures are BetG8 calculations.
18+ only. This guide explains a betting measurement as of November 2026. It is not legal, tax or financial advice and not a recommendation to bet or trade. If gambling stops being fun, help is available at 1-800-GAMBLER.