What Is Arbitrage Betting?
Arbitrage betting (often called "arbing") is the practice of placing bets on all possible outcomes of an event across different bookmakers so that the combined implied probability of your bets falls below 100%. When that happens, you guarantee a profit regardless of the result.
It works because different bookmakers price events differently. When bookmaker A prices Team X to win at $2.10 and bookmaker B prices Team Y to win at $2.10 in the same match, the combined implied probability is 95.2% — not 100%. That 4.8% gap is your guaranteed margin.
How It Works: A Worked Example
Example: Two-Outcome Arb
| Outcome | Bookmaker | Decimal Odds | Implied Probability |
|---|---|---|---|
| Team A wins | Bookmaker 1 | $2.10 | 47.6% |
| Team B wins | Bookmaker 2 | $2.10 | 47.6% |
| Total implied probability | 95.2% | ||
Because the total is below 100%, an arb exists. Here is the stake calculation for a $100 total outlay:
- Stake on Team A (Bookmaker 1): $50
- Stake on Team B (Bookmaker 2): $50
- If Team A wins: return $50 × $2.10 = $105
- If Team B wins: return $50 × $2.10 = $105
- Profit either way: $5 (5% ROI)
Use the Arbitrage Calculator to find the correct stakes for any arb, including three-way and custom-outcome events.
Is Arbitrage Betting Legal in Australia?
Yes. There is no law in Australia that prohibits punters from placing bets at multiple bookmakers to exploit price differences. The Interactive Gambling Act 2001 regulates what services bookmakers can offer, not how punters choose to bet across them.
The practical risk is account restriction, not legal exposure. Bookmakers are private businesses and can limit or close accounts at their discretion. Most Australian bookmakers will limit the maximum bet size on accounts they identify as arbers, sometimes within weeks of identifying the pattern. This is a commercial decision on their part, not a legal one.
Which Australian Bookmakers Are Arb-Friendly?
No Australian bookmaker actively encourages arbitrage, but some are significantly more tolerant than others.
| Bookmaker | Arb Tolerance | Notes |
|---|---|---|
| Betfair Exchange | High | Peer-to-peer exchange. No bookmaker to restrict you. Lay side means you can cover outcomes directly. |
| bet365 | Medium | Restricts heavy arbers but tolerates low-volume accounts for longer than most. |
| Unibet | Medium | Part of a large group; restriction processes are somewhat slower than smaller operators. |
| Ladbrokes | Low | Active account management; restricts winning accounts relatively quickly. |
| Neds | Low | Same group as Ladbrokes; similar restriction patterns. |
| dabble | Medium | Smaller operation; less aggressive with restrictions but also lower limits overall. |
Betfair Exchange deserves special mention. Because it is a peer-to-peer platform where punters bet against each other rather than against the house, Betfair has no commercial incentive to restrict winners. You can lay outcomes directly on Betfair, making it the most natural arb partner when combined with any back-bet bookmaker.
How to Find Arbitrage Opportunities
Manual arb hunting across multiple bookmaker sites is tedious and most opportunities disappear within minutes. The main approaches are:
- Odds comparison sites: Sites that aggregate odds in real time make it easy to spot when two bookmakers have diverged significantly on the same market.
- Arb scanning services: Paid services like OddsMonkey and RebelBetting continuously scan for arbs across dozens of bookmakers and alert you when one appears. Subscriptions typically cost $50–$150/month.
- Betfair Exchange monitoring: Watching the Betfair lay market alongside traditional bookmaker prices is a reliable way to spot overpriced back odds at retail bookmakers.
Common Mistakes
- Slow execution: Arb windows close fast. By the time you place your second bet, the odds on the first may have moved. Always try to place the less liquid side (usually the back bet at a retail bookmaker) first.
- Ignoring withdrawal delays: Your profit is only realised once you can withdraw from both accounts. A bookmaker that takes five days to process a withdrawal ties up capital unnecessarily.
- Obvious betting patterns: Consistently betting on obscure markets at maximum stake the moment an arb appears is the fastest way to trigger a review. Varying timing and stake size extends account life.
- Not accounting for exchange commission: Betfair charges 5% commission on net winnings on the exchange. Factor this into your arb calculation or your apparent profit evaporates.
Risk Management
Arbing is not risk-free. The main risks are:
- Void bets: If one leg is voided (e.g. a scratching in racing) and the other settles, you may end up with an unhedged position.
- Account restriction: Once an account is limited, it may return less than the original stake on existing bets in some cases. More often you will simply lose access to the prices that made the arb work.
- Operator error: Occasional mis-priced odds that look like arbs are sometimes palpable errors. Bookmakers may void these bets after the fact.
Start with small stakes across a wide range of accounts rather than deploying large sums through a small number of bookmakers. This limits your exposure to any single account restriction event.
Frequently Asked Questions
Returns of 2%–8% per arb are typical for two-outcome events. The limiting factor is account longevity. Most arbers report their retail bookmaker accounts being limited within 3–6 months of sustained arbing, which restricts access to the best odds. Keeping accounts active with some recreational bets and not exclusively arbing extends their useful life.
Gambling winnings are generally not taxable in Australia for recreational punters. If arbing becomes a business activity — conducted in an organised, systematic way with a profit motive — the ATO could consider it assessable income. Most individual arbers are treated as recreational gamblers for tax purposes, but you should seek independent tax advice if you are arbing at significant scale.
Technically yes — you can back an outcome on one market and lay it on another if a price discrepancy exists. In practice, Betfair's own markets are efficient and arbs within the exchange are rare. The more common use is pairing a Betfair lay against an overpriced back-bet at a retail bookmaker.
Dutching means splitting your stake across multiple outcomes at the same bookmaker to guarantee the same return regardless of which outcome wins. It is not quite the same as arbing because there is no guaranteed profit — you are simply spreading risk within one platform. True arbing requires prices across different bookmakers to create a combined implied probability below 100%.
Use the Arbitrage Calculator to calculate exact stakes and guaranteed profit for any arb opportunity. Always gamble responsibly. For free and confidential support call 1800 858 858.