What is CLV (Closing Line Value) and Why It Matters
Closing line value (CLV) measures whether the odds you bet at were better or worse than the final market price before the event started. Consistently beating the closing line is strong evidence of a genuine betting edge.
What is closing line value?
When a bookmaker first opens a market, the odds are less informed. As the event approaches, more money comes in from sharp bettors, odds compilers refine their estimates, and the price stabilises at something close to the true probability. The final odds just before kickoff are called the closing line.
CLV is the difference between the odds you got and the closing odds. If you bet at 2.10 and the market closed at 1.95, you got 7.7% better than the market's final assessment. That is positive CLV. If you bet at 2.10 and the market closed at 2.20, the market moved away from you. That is negative CLV.
A single bet tells you little. But if you consistently get better odds than the closing line across hundreds of bets, that is strong evidence you are finding real edges rather than getting lucky.
Why the closing line matters
The closing line is the most accurate odds the market produces. By the time an event starts, the line has absorbed information from sharp bettors, syndicates, and professional traders. It is not perfect, but it is the best available estimate of the true probability.
If you consistently beat it, you are getting odds that reflect a more accurate view of probability than the market eventually settles on. That is what an edge looks like, in mathematical terms.
This is why professional bettors care more about CLV than about their win rate or even their P&L in the short term. A bettor who is beating the closing line by 3% on average is almost certainly profitable in the long run, even if a bad run of results has temporarily pushed their P&L into the red. A bettor with a high win rate but negative CLV is getting lucky and likely to regress.
How to calculate CLV
The formula is straightforward.
CLV% = (bet odds / closing odds - 1) × 100
If you bet at 2.10 and the closing odds were 1.95: CLV% = (2.10 / 1.95 - 1) × 100 = 7.7%
If you bet at 1.90 and the closing odds were 2.05: CLV% = (1.90 / 2.05 - 1) × 100 = -7.3%
To get a cleaner number, use the no-vig closing price rather than the raw closing odds. VigBreak calculates CLV using no-vig closing odds from a sharp reference, which removes the bookmaker's margin before measuring your edge.
CLV vs actual results
P&L is the number people usually focus on, but it is a noisy signal in the short term. Win or lose on any individual bet is largely random. Even with a 5% edge, you can lose 15 bets in a row without anything having gone wrong with your strategy.
CLV is less noisy because it is measured independently of the outcome. It tells you whether you got a good price before the result happened. A positive CLV result on a losing bet still means you made a good decision. The result was bad luck, not a bad bet.
Over a large sample (typically several hundred bets or more), P&L and CLV should converge. If you have strong positive CLV over 500 bets but negative P&L, you are running below expectation and likely to correct. If your P&L is positive but CLV is flat or negative, you are running above expectation and may be due for a reversion.
Tracking both gives you a much clearer picture of whether your process is working.
How VigBreak tracks CLV
VigBreak records the odds at the time each paper bet is placed, then compares them to the closing odds once the event has started.
The stats page shows aggregate CLV across all settled EV bets, a histogram of CLV distribution, and CLV broken down by bookmaker and by sport. The P&L chart shows actual profit alongside a dotted CLV line, so you can see how the two track each other over time.
Every bet in the history is public. Wins, losses, and CLV values are all shown on the bets page, with nothing filtered out or backdated.