The central idea
Closing Line Value compares the price taken with a later closing price for the same outcome and rules. It measures price movement, not settlement.
CLV = original odds ÷ closing odds − 1
Worked example
Taking 2.20 before the same market closes at 2.00 gives +10% odds-ratio CLV. The implied probability moves from 45.45% to 50%, a separate change of 4.55 percentage points.
Limits of the calculation
The closing snapshot must represent the same market and settlement rules. Positive CLV on one selection does not prove long-term profitability.