Arbitrage calculator
Check whether two complementary prices leave a theoretical arbitrage, and split a total stake between them.
The best price you can get on one outcome.
The best price on the complementary outcome, usually at another book.
Stake split
This is a theoretical split. Whether it can be executed depends on stake limits, on both prices still standing when the second stake lands, and on both sides settling rather than voiding. A voided leg leaves the other side exposed.
How it is calculatedOpenClose
Add the implied probabilities of the two complementary prices. Below 1 the market is theoretically arbitrable, and the total stake splits in proportion to those implied probabilities. The return is the total divided by that sum, whichever side lands.
- An arbitrage exists on paper when the two complementary prices imply less than 100% in total.
- The split is proportional to the implied probabilities, which makes the return the same whichever side lands.
- Execution is a separate question. Stake limits, a price that moves before the second stake lands, and a leg that voids while the other stands can all remove the result.
Worked example, illustrative
+115 at one book, -105 at another
- 1The two prices imply 46.51% and 51.22%, which add to 97.73%.
- 2The theoretical margin is 2.27%.
- 3A total of 100 splits into 47.59 and 52.41, returning 102.32 whichever side lands.
These figures are an illustration of the formula, not a claim about any real market.
Related guidance
Research only. This tool does arithmetic on numbers you type. It does not place bets, submit entries, estimate a probability for you, or tell you what to risk. If gambling stops being fun, call 1-800-GAMBLER.