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Arbitrage
calculator.

Two bookmakers offering opposite outcomes at prices that imply less than 100% combined probability? That's an arb. The calculator works out whether the maths is real, and exactly how to distribute stakes to lock in guaranteed profit.

Calculator

Two-way arbitrage

Enter the best decimal odds for each side of a market across different bookmakers.

Enter both odds and total stake to check for arbitrage opportunity

What this calculator does

If two bookmakers price a two-outcome market with combined implied probability under 100%, an arb exists. The calculator: (1) detects whether the maths produces an arb, (2) splits your total stake across both outcomes in proportion to the odds, so the return is identical regardless of which outcome wins, (3) shows your guaranteed profit and ROI percentage.

Worked example: outcome A at 2.10 (47.6% implied) and outcome B at 2.05 (48.8% implied) add up to 96.4%, a 3.6% arb. With R1,000 in total, stake R493.98 on A and R506.02 on B. Whichever wins, you get back about R1,037.35, a profit of R37.35 (3.7%).

The realities of arbing

Margins are small

Real arbs are typically 1-3% on the total stake. To make R1,000 profit you need R30,000-R100,000 in combined stakes. That's significant capital tied up across multiple bookmaker accounts.

Detection is fast

Bookmakers watch for arbing. Stakes that exactly match bets on the other side elsewhere, very quick placement and shared devices or IP addresses can all flag an account. Stake limits and account closures often follow.

Prices move

Between placing the first and second legs, the odds at the second bookmaker can shorten and wipe out the arb. Speed matters, and arbing by hand on a phone often fails because the second price has gone by the time you place it.

Voided bets are catastrophic

If a tennis match is abandoned, a horse withdrawn, or a rule change voids one leg, you're suddenly holding a one-sided bet at potentially terrible prices. This is the biggest single risk in arbing.

For most SA bettors

Arbing is interesting betting maths but rarely worth the effort. For most recreational punters, the time spent finding and placing arbs would be better spent on careful value betting. The calculator is for learning: it shows you when an arb exists. Whether to chase one is a separate question with real downsides.

Continue learning

Common Questions

You asked.

Arbitrage betting ("arbing") means betting on every possible outcome of an event at different bookmakers when the prices add up to less than 100% implied probability. The result is a locked-in profit whatever happens, usually 1% to 5%. The catch is that arbs are rare and small, and bookmakers look for and limit accounts that use them.

Yes, arbitrage betting is legal: you are placing ordinary bets with licensed bookmakers. But bookmakers' terms usually let them close, restrict or limit accounts they believe are arbing, and many look for it through stake patterns, rapid bets across markets and shared devices or IP addresses. Limits or closure often follow. It is legal; keeping it going is the hard part.

Most arbs offer 1-3% profit on the total stake. R10,000 in combined stakes might yield R200 profit. To make meaningful money requires huge bankroll spread across many bookmaker accounts, fast execution before prices change, and tolerance for accounts being limited. For most SA bettors, arbing is technically possible but not practically worth the operational complexity. The exception is very high-volume professional bettors with dedicated infrastructure.

Five main risks: (1) Account limits: bookmakers can cut your maximum stake sharply once they spot you. (2) Voided bets: if one leg is voided (a rule change or an abandoned event), the other becomes an ordinary one-sided bet. (3) Price moves: odds can shift between the two legs and wipe out the arb. (4) Stake errors: a miscalculated split can turn a locked-in profit into a loss. (5) Bonus rules: some bookmakers void winnings from arbing with bonus funds.