Closing line value (CLV) compares the odds a bettor obtained when placing a wager with the odds available at the moment the market closes, just before the event begins. If a bettor regularly takes prices that are better than the closing line, they are said to be achieving positive closing line value.
The concept rests on the idea that the closing line is unusually accurate. By the time a market closes, it has absorbed large volumes of money, late news such as team confirmations, and the opinions of sharp bettors. As a result, the closing odds are often treated as one of the best available estimates of an outcome’s true probability.
Suppose you back a hypothetical selection at decimal odds of 2.20. By the start of play, the same selection has shortened to 2.00 across the market. You secured a price implying 45.5% probability, whereas the closing line implies 50%. Because you obtained a longer price than the eventual consensus, you achieved positive CLV of roughly 10% in odds terms, regardless of whether that particular bet won or lost.
A key distinction is that CLV measures the quality of your decision, not the outcome. A bet can win yet show negative CLV, and a losing bet can still show strong positive CLV. Over a small sample, results are dominated by variance, so many bettors track CLV as a more stable signal of whether their process is sound.
CLV is not a guarantee of profit. It depends on being able to bet at the prices observed, and operators that limit winning accounts can make consistent positive CLV difficult to act upon. The reliability of the closing line as a benchmark also varies by market: deep, liquid markets close more efficiently than thin ones, so CLV is a stronger signal in high-volume events.