CORTENOpening odds are the first price recorded for a match in a data set; closing odds are the last price recorded before kick-off. The percentage change is (closing − opening) / opening × 100. Two observations alone do not describe the movement in between or the reason for the change.
The opening price is the first price recorded for a match in a given dataset. The closing price is the last price recorded in that dataset before kick-off. Different providers may not record the same moments, so do not treat two prices as equivalent unless the date, time and data coverage are stated.
What do opening and closing tell you?
Odds are a way of displaying a price in the market. The difference between opening and closing shows how that price changed between two recorded points. These two numbers alone cannot tell you how many times it changed in between, or exactly why.
How is the change calculated?
Say the opening price is 2.10 and the closing price is 1.85. The percentage change is (1.85 − 2.10) / 2.10 × 100 = −11.90%. The implied probability is about 47.62% at the open and about 54.05% at the close. Both include the market margin and should not be read as the true probability of the outcome.
Calculate with your own numbers
What can you not conclude?
A drop on its own is not evidence of team news, an unusual event, the result or manipulation. Sources, recording times, market margins and missing data all affect the comparison. When you look at past matches, show the sample size too.
Further reading: Why sample size matters · Methodology.
Last updated: 28 October 2026 · Responsible: Cortenscore editorial team · Spotted an error? Report a correction. The worked example is illustrative; it is not a real match or a recommendation to invest or bet.