Convert odds between decimal, American (moneyline) and fractional formats with the implied probability, or turn a win probability into betting odds.
Odds Formula and Method
Decimal odds = total return / stake
Decimal odds describe total returned per unit staked. Fractional odds describe profit relative to stake. Positive American odds describe profit on a 100-unit stake; negative American odds describe the stake needed for 100 units of profit. Converting formats keeps the underlying offered price unchanged.
How to Use This Calculator
Select the source odds format or entered probability, enter its value, then calculate. Review the equivalent formats and open the calculation details for formulas and assumptions.
Worked Example
With the example inputs in the table, the result is 2.5 decimal. These formats describe the same offered price.
Implied probability = 100 / decimal odds
Input and Example Guide
| Input or category | Example or weight | Entry guidance |
|---|---|---|
| Method | Convert an offered price | Choose the convention that applies to your record. |
| Input odds format | Decimal odds | Choose the convention that applies to your record. |
| Offered odds (selected format) | 2.5 | Use the stated unit; retain available precision. |
Interpreting the Result
The reciprocal of decimal odds is the cash-stake break-even probability. It is an implied price probability, not an independent estimate of an outcome’s chance. Entering a probability in the reverse method gives its corresponding zero-margin price. Rounded display prices may differ slightly when converted back.
Offered-price implied probability may reflect market margin; it is not a measured chance of winning.
Assumptions and Common Input Errors
These formats describe the same offered price. Keep settlement conditions consistent when comparing prices. Displayed formats are rounded; calculations retain available numeric precision.
Saving and Revising a Scenario
A successful calculation is saved in this browser and can be restored on the next visit. Editing an input marks the saved result as out of date until recalculated. Reset clears the inputs, result and saved scenario.
Sources
Betfair Help: odds formats and Betfair betting help. Arithmetic and scenario assumptions are specified above.
