Calculate odds from your inputs, with a result breakdown and worked steps.
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 result and any applicable method before entering the visible values. Check the selected record, unit and scoring conventions before calculating. Review the primary result and its breakdown, then open the calculation steps to see how the inputs were used.
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.
Implied probability includes the market margin; it is not a measured chance of winning.
Assumptions and Common Input Errors
These formats describe the same offered price. Keep the same currency and settlement conditions throughout a scenario. Displayed currency amounts are rounded to two decimals; calculations retain precision unless cent allocation is explicitly described.
Saving and Revising a Scenario
A successful calculation is saved in this browser and can be restored on the next visit. Editing an input clears the old result so it is not mistaken for an updated calculation. Reset returns the example inputs and clears the saved result.
Sources
Betfair Help, Decimal Odds and Stake-Inclusive Returns, reviewed 2026. Arithmetic and scenario assumptions are specified above.