Arbitrage Calculator

How arbitrage betting works

Add the implied probability of each outcome (1 ÷ decimal odds). If the sum across all bookmakers is under 100%, betting the right amount on each outcome locks in the same profit no matter which one wins — the stake split above shows exactly how to divide your total stake to achieve that. This works because bookmakers set their own odds independently, each building in their own margin against their own view of an event, and those views don’t always agree — occasionally by enough that betting every outcome across the disagreeing books costs less, in total, than the guaranteed payout.

The underlying principle is called "surebetting" for a reason: unlike ordinary betting, where you’re taking a position on an uncertain outcome, a correctly executed arbitrage bet removes the uncertainty entirely — you win a fixed amount regardless of which selection comes in, because you’ve covered every possibility. What you’re actually trading on isn’t the game’s result at all; it’s the temporary pricing disagreement between two or more bookmakers.

A worked two-way example

Suppose Bookmaker A offers 2.10 on Team X to win a tennis match, and Bookmaker B offers 2.05 on Team Y (the opponent) to win the same match. Implied probability on A is 1 ÷ 2.10 ≈ 47.6%, and on B is 1 ÷ 2.05 ≈ 48.8%. The combined implied probability is 96.4% — under 100%, meaning a risk-free arbitrage exists worth roughly 3.6% of your total stake. To lock in an equal profit regardless of outcome, you’d stake proportionally more on the outcome with lower odds: for a €1,000 total stake, roughly €511 on Team X at 2.10 and €489 on Team Y at 2.05 returns about €1,073 either way — a guaranteed €73 profit no matter which side wins, before accounting for the practical risks below.

Why arbitrage opportunities are rare and fragile

Bookmakers actively price to avoid arbitrage — their margin exists precisely so that, under normal circumstances, no combination of prices across their own market lets a bettor profit risk-free. Genuine cross-bookmaker arbitrage only appears when two or more operators temporarily disagree enough on a price to erase their combined margins, which typically happens around late odds moves, in-play markets reacting to a fast-changing game state, or smaller/regional bookmakers slower to adjust to news that’s already moved the bigger books. These windows tend to close within minutes as odds converge, which is why arbitrage in practice is a speed-and-monitoring exercise as much as a math one.

It’s also worth being explicit about what this calculator can and can’t protect you from. It correctly identifies whether the odds you enter represent a mathematical arbitrage and computes the exact stake split for a guaranteed return — but it has no way of knowing whether those odds will still be available by the time you’ve placed every leg, whether a bookmaker will limit your stake or void the bet, or whether an operator’s account-restriction policy will flag the pattern. Those are real, well-documented risks in arbitrage betting that exist entirely outside the math.

Two-way versus three-way markets

The same logic extends to three-way markets (win/draw/loss, as in football), just with a third implied probability added to the sum. Three-way arbitrage opportunities are generally rarer than two-way ones, simply because three independent bookmakers all disagreeing enough, simultaneously, to push the combined implied probability under 100% is a stricter condition to satisfy than two. When they do appear, the stake-split math works identically — allocate stake to each outcome in proportion to its odds so the payout is equal regardless of which of the three results occurs.

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