What Is the Difference Between Opening and Closing Lines?

The opening line is the first price a book posts on a game. The closing line is the last price available before the game starts. Between the two, the market absorbs injury news, lineups, weather and the bets of its sharpest customers, so the close is generally the most accurate estimate the market ever produces of each side's chance of winning.

That is why serious bettors measure themselves against the close rather than against results. If you routinely bet at prices better than where the market settles, you are probably doing something right, even through a losing month. If the line routinely moves against you after you bet, a winning month is probably luck.

What is an opening line?

It is the book's first draft: a price built from its own model, a supplier's feed or a market-maker's number, published before much money or news has arrived. Openers come out days ahead for NFL games and the night before or morning of for most NBA, MLB and NHL games.

Openers are the least-tested prices in the market, and books know it. They typically accept smaller maximum stakes early and raise limits as the game approaches and the price firms up. An opener can be wrong in either direction; it has simply had less scrutiny.

It is not a wild guess, though. Tobias Moskowitz's 2021 Journal of Finance study, using opening and closing lines from the same source across 117,442 contracts on NFL, NBA, MLB and NHL games, found that opening prices were set efficiently on average with respect to teams' past performance. Steven Levitt's NFL data, published in 2004, found the spread at kickoff was within one point of the Tuesday spread in 90% of games. Most of the work is done at the open.

What is a closing line?

The price at the moment betting stops — kickoff, tip-off, first pitch. By then:

• the league's scheduled injury news is out (the NBA's 2025–26 rules, the latest posted as of September 2026, for example require teams to designate statuses by 5 p.m. local time the day before a game and to file a game-day report between 11 a.m. and 1 p.m. local, updated through the day);
• starting lineups and pitchers are usually confirmed;
• the books have seen which customers bet which side, and at what stakes;
• the market-makers, who take the largest bets at the thinnest margins, have been hit by everyone who thought the price was wrong.

A low-margin book that openly takes arbitrage bets — Pinnacle says as much on its own site — has an incentive to let informed money correct its price, because that is how it stays accurate enough to survive on a thin margin. Its closing number is the usual reference for "the close".

Why is the closing line the best estimate?

Because it has the most information and has survived the most money. Every bettor who thought the price was wrong had the chance to bet into it, and the book had every reason to move when the right people did.

The best public evidence for it is a test of whether beating the close predicts profit. Joseph Buchdahl ran one on 87,960 pairs of pre-closing and closing soccer odds from Pinnacle, covering four seasons from 2012/13, published on football-data.co.uk in August 2016. He took the ratio of each earlier price to the closing price — a measure of how much a bettor would have beaten the close by — and compared it with the realised return. The relationship had a slope of almost exactly 1.00: in other words, beating the close by a given percentage was worth about that percentage in realised returns across the sample, less the bookmaker's margin, which the analysis left in.

The close is not flawless. Moskowitz found that about half of the average move between open and close was reversed by the result — the crowd pushes some prices too far, particularly toward teams on hot streaks. But the mispricing he measured was smaller than the vig, so nobody could bet against it profitably. "Best available estimate" is the claim, not "perfect".

Why does beating the closing line matter?

Results are noisy. A bettor at -110 needs to win 52.4% to break even. Over 200 bets, one standard deviation of luck is about 3.5 percentage points of win rate — a skilled bettor can finish below 50%, and an unskilled one above 55%, without either telling you much. It takes thousands of bets for results alone to separate skill from variance.

Closing line value (CLV) converges much faster, because you learn something from every bet on the day it settles, regardless of the score.

A worked example. You bet Team A at +120 on Tuesday. By kickoff the market-maker's price is -110 / -110, which with the margin removed is 50% / 50%.

• Your price, in decimal: 1 + 120 ÷ 100 = 2.20
• The fair closing price at 50%: 1 ÷ 0.50 = 2.00
• CLV = 2.20 ÷ 2.00 − 1 = +10%
• Expected value if the close is right: 0.50 × 2.20 − 1 = +10% of the stake

Now the other direction. You bet Team B at -105 and the market closes at -125 on B / +105 on A.

• -125 implies 55.56%; +105 implies 48.78%; total 104.34%
• B's no-margin probability: 55.56 ÷ 104.34 = 53.25%
• Your decimal price: 1 + 100 ÷ 105 = 1.952
• Expected value: 0.5325 × 1.952 − 1 = +4.0%

Team B can lose that game and the bet was still good. Team A can win and the Tuesday bet was good for a different reason. Over hundreds of bets, the average CLV is the number that tells you whether your process finds prices better than the market's final answer. The Academy's closing line value guide covers how to record and calculate it properly, including which book's close to use.

Where the opener still matters

If the close is the best estimate, why bet early at all? Because the opener is where the gaps are largest. A book that posts a number before the market has tested it is more likely to be wrong, and the bettor who spots it gets the better price. That is precisely why books cap early stakes.

Three honest caveats:

1. Beating the opener is not the same as beating the close. If you bet at the open and the line comes back to where you bet, you had no edge on that one.
2. A single book's close can be a bad reference. A retail book that copies late or hangs a wide margin can close at a number the rest of the market has left. Use a sharp, low-margin close, with the margin removed.
3. Positive CLV does not guarantee profit over any stretch you can live through. It raises the odds that your results reflect skill; variance still decides any given month.

What to take from this

Openers are drafts, closers are the market's verdict, and the gap between the price you took and the verdict is the most useful number you can track. Levitt found little evidence that the bettors in his contest data could beat the book systematically, which is the normal state of affairs — most people who track CLV discover they don't beat the close. That is information too.

The previous guide in this series explains why lines move between the two; the next looks at sharp money vs public money and what really drives those moves.