#131 · Odds Probability & Margin

Opening vs Closing Odds Calculator

Compare an opening price with its closing price and measure the change in odds, implied probability, and bettor-facing closing-line value.

Calculator

Enter assumptions
decimal odds
decimal odds
amount
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How to use this calculator

  1. Enter the market values in the labelled fields.
  2. Keep odds in decimal format and amounts in one currency.
  3. Select the settlement option when shown, then press Calculate.
  4. Compare the main result with the supporting figures and rule note.

Formula and calculation

CLV = (opening odds ÷ closing odds − 1) × 100. Implied probability = 100 ÷ decimal odds.

CLV = (opening odds ÷ closing odds − 1) × 100. Implied probability = 100 ÷ decimal odds.

The calculator runs entirely in your browser and sends no betting data to a server.

Worked example

The default fields provide a worked example. Press Calculate to recompute every displayed value from those inputs; changing any input marks the result for an update.

CheckMeaning
Main resultClosing-line value
PrecisionFull precision internally; sensible display rounding

Assumptions and limits

This tool applies the formula shown above to the supplied numbers. It does not retrieve live odds or predict an outcome. Market settlement, deductions, commissions, voids, and rounding can differ by operator and jurisdiction.

Use the result as an audit aid and check the market’s official rules before relying on it.

FAQ

What inputs does the Opening vs Closing Odds Calculator require?

It uses only the values shown in the calculator. Enter decimal odds and monetary amounts in consistent units where applicable.

How is the main result calculated?

CLV = (opening odds ÷ closing odds − 1) × 100. Implied probability = 100 ÷ decimal odds. Intermediate values retain full JavaScript precision and displayed figures are rounded.

Does rounding change the settlement?

The calculator rounds only for display. A bookmaker may round at a different stage, so a small account-level difference is possible.

Can operator rules change this result?

Yes. Voids, dead heats, commission tiers, deductions, overtime and market-specific settlement can differ. Check the rules attached to the actual market.

Does this result predict a winning bet?

No. It is a transparent mathematical estimate from the entered assumptions and does not predict events or guarantee a return.

Calculation notes

ItemRule
OddsDecimal format
RoundingDisplay stage only
DataProcessed locally