Closing line value (CLV)

Closing line value compares the odds a bettor received at the moment they placed a bet with the "closing line," the final odds available just before the event begins. If a bettor took a team at odds better than where the market closed, they captured positive closing line value, meaning they beat the market's own final assessment of the probabilities involved, regardless of whether the bet actually won.

CLV is usually expressed as a percentage difference between the implied probability of the bettor's odds and the implied probability of the closing odds. Because betting markets absorb information from sharp bettors, public money, and late news right up to kickoff, the closing line is widely treated as the most accurate available estimate of true probability, more reliable than any single bettor's opinion.

Serious bettors track CLV rather than short-run win rate because win rate over a small number of bets is dominated by variance, while consistently beating the closing line, even on bets that individually lose, is associated with positive expected value in the long run. The common pitfall is judging betting skill purely by whether recent bets won or lost; a bettor can show strong CLV and still lose money over a small sample, or show poor CLV and get lucky, without either outcome reflecting their actual edge.