Key takeaways
- Arbitrage betting (a "surebet" or "arbing") = backing every outcome across different bookmakers for a guaranteed profit.
- A surebet exists when the combined implied probability V = Σ(1/odds) is below 1 (100%).
- It is legal, but bookmakers may limit or close accounts that arb.
- Margins are usually small (~1–5%), so it relies on bankroll, volume and speed.
- Use our free surebet calculator to size every stake instantly.
What is arbitrage betting?
Arbitrage betting — also called a surebet or simply arbing — is a technique where you place bets on all possible outcomes of an event, each at a different bookmaker, so that whichever result occurs you come out with a profit. It works because bookmakers don't always agree on the odds. When one bookmaker prices one outcome generously and another prices the opposite outcome generously, the combined odds can guarantee a return.
Unlike normal betting, a surebet has no rooting interest — you don't care who wins. The profit is locked in by mathematics the moment all bets are placed.
How does arbitrage betting work?
Imagine a tennis match between Player A and Player B. Bookmaker 1 offers 2.10 on Player A; Bookmaker 2 offers 2.10 on Player B. If you stake €50 on each:
- If Player A wins: 50 × 2.10 = €105 back, for €105 − €100 staked = €5 profit.
- If Player B wins: 50 × 2.10 = €105 back, again a €5 profit.
Either way you finish ahead. That is a surebet. In practice the stakes usually aren't equal — you split them so the payout is identical whichever side wins, which is exactly what an arbitrage calculator does for you.
How do you calculate an arbitrage bet?
Add up the inverse of each outcome's odds: V = 1/odds₁ + 1/odds₂ + … + 1/oddsₙ. If V is less than 1, a guaranteed profit exists. Your profit margin is (1 / V − 1) × 100%, and the stake on each outcome is (total stake / V) / odds.
Want the full breakdown with worked examples? See our arbitrage betting formula guide. You rarely need to do this by hand, though. Pick the version that matches your market: 2-way (e.g. tennis, Over/Under), 3-way (1X2 football), 4-way, 5-way or 6-way — or the main 2–15 way calculator.
Is arbitrage betting legal?
Yes — arbitrage betting is legal wherever betting itself is legal. You are simply placing ordinary bets. What it does do is breach the terms of service of many bookmakers, who do not want customers that win consistently. They reserve the right to limit your maximum stake (“gubbing”) or close your account. So while it is not against the law, it can be against an individual bookmaker's rules. (See Wikipedia: Arbitrage betting.)
Is arbitrage betting profitable?
It can be, but set realistic expectations. Individual surebets usually return a small margin, roughly 1–5%. To turn that into meaningful money you need a decent bankroll spread across several bookmakers, a steady supply of opportunities, and the discipline to place bets quickly. It is a grind based on volume and consistency, not a get-rich-quick scheme.
What are the risks of arbitrage betting?
The maths is sound; the risks are in execution:
- Odds movement — odds can change between placing your first and second bet, breaking the arb.
- Account limits & closures — bookmakers may restrict or “gub” consistent winners.
- Voided / palpable-error bets — if a bookmaker cancels one leg (e.g. an obvious pricing error), you're left exposed on the other.
- Stake limits — you may not be allowed to stake enough to balance the bet.
- Human error — mistyping odds or stakes. Always double-check with a calculator.
Arbitrage betting vs matched betting
They're related but not identical. Arbitrage exploits odds differences across bookmakers. Matched betting focuses on extracting value from free bets and bonuses, often using a betting exchange. If you have a free bet, our free bet calculator shows how to convert it into guaranteed profit.
How to get started with arbitrage betting
- Open accounts with several bookmakers (more bookmakers = more arbs).
- Find opportunities — manually comparing odds, or with an odds-comparison service.
- Use a surebet calculator to size each stake.
- Place every leg quickly, before the odds move.
- Start small, keep records, and spread your activity to stay under the radar.
Frequently asked questions
- Is arbitrage betting legal?
- Yes. Arbitrage betting is not illegal anywhere that betting itself is legal. However, it breaches the terms of service of many bookmakers, who may limit stakes or close accounts of bettors they identify as arbers.
- Can you actually make money from arbitrage betting?
- Yes, the profit is mathematically guaranteed once both bets are placed. But margins are small (typically around 1-5%), so returns depend on volume, available bankroll and acting quickly before odds change.
- Why do bookmakers ban arbitrage bettors?
- Bookmakers profit from losing customers. An arber wins consistently, so bookmakers reserve the right (in their T&Cs) to restrict stakes or close accounts that show arbitrage patterns.
- Is arbitrage betting risk-free?
- The maths is risk-free, but execution is not. Odds can change before you place the second leg, a bet can be voided, stakes can be limited, or you can make an input error. Careful, fast execution keeps it close to risk-free.
- How much money do I need to start?
- You can start with any amount, but because margins are small you need a reasonable bankroll spread across several bookmaker accounts to make meaningful profit.