Arbitrage calculator
How to split a stake across two books so both sides pay the same, and whether the prices leave a profit.
Result
- Stake at +110
- $49.40
- Stake at +105
- $50.60
- Payout either way
- $103.73
- Result either way
- $3.73
- Return on the total stake
- 3.7%
- Implied chances added together
- 96.4%
Arbitrage: both outcomes finish ahead
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How it works
An arbitrage, or arb, is a pair of prices at two different books that pay back more than you staked whichever side wins. It happens when the two books disagree by more than their margins.
Enter the odds on each side and the total you want to stake. The calculator splits the stake so both outcomes pay the same amount, and shows what's left after both bets.
Most pairs of prices aren't arbs. When the two implied chances add up to more than 100%, the same split locks in a loss, and the result says so.
How do you calculate an arbitrage bet?
Convert each price to the chance it implies and add them up. Take one side at +110 and the other at +105: 47.6% + 48.8% = 96.4%. Anything under 100% is an arb.
To split $100, stake each side in proportion to its implied chance: $49.40 at +110 and $50.60 at +105. Either bet pays $103.73 if it wins, so you finish $3.73 ahead, or 3.7% of the total stake.
Why isn't every price difference an arb?
Each book builds its margin into both sides, so two prices have to differ by more than that margin before an arb appears. At -110 on both sides, the implied chances add up to 104.8%, and splitting $100 locks in a loss of $4.55.
Real arbs are uncommon and don't last, and both bets have to be placed before either price moves. Each book's house rules cover voided bets and obvious pricing errors, so read them before counting on one. To even out a bet you've already placed, use the hedge calculator.