What Is Arbitrage Betting?
Arbitrage betting (commonly called "arbing") is a technique where you place bets on all possible outcomes of a sporting event across different bookmakers, taking advantage of pricing discrepancies to guarantee a profit regardless of the result.
It works because bookmakers sometimes price the same event differently. When the combined implied probabilities of all outcomes across multiple books falls below 100%, an arbitrage opportunity — or "arb" — exists.
A Simple Arbitrage Example
Suppose two bookmakers price a tennis match as follows:
| Bookmaker | Player A Odds | Player B Odds |
|---|---|---|
| Bookmaker 1 | 2.10 | 1.80 |
| Bookmaker 2 | 1.85 | 2.20 |
The best odds available are: Player A at 2.10 (Bookmaker 1) and Player B at 2.20 (Bookmaker 2).
Combined implied probability: (1 ÷ 2.10) + (1 ÷ 2.20) = 47.6% + 45.5% = 93.1%
Because the total is under 100%, an arb exists. The profit margin is approximately 100 – 93.1 = 6.9%.
How to Calculate Arbitrage Stakes
To calculate how much to bet on each outcome for a desired total profit, use the following:
Individual stake = (Total investment × Individual implied probability) ÷ Total implied probability
For a £1,000 total investment in the example above:
- Stake on Player A: (£1,000 × 0.476) ÷ 0.931 = £511
- Stake on Player B: (£1,000 × 0.455) ÷ 0.931 = £489
Whichever player wins, the return is approximately £1,073 — a profit of roughly £73 on a £1,000 investment.
Where Arbs Come From
- Different risk models: Bookmakers use different algorithms and traders, leading to pricing discrepancies.
- Slow odds updates: When news breaks (injury, team selection), some books update faster than others.
- Promotional boosts: Enhanced odds promotions can create temporary arb windows.
- Exchange vs. bookmaker differences: Betting exchanges (like Betfair) often offer better prices on some sides of a market.
Tools for Finding Arbitrage Opportunities
Manual arb hunting is extremely time-consuming. Most arbers use dedicated software or odds comparison services that scan multiple bookmakers in real time and alert you to opportunities. These tools typically require a subscription, and arbs often close within minutes of appearing.
The Real Risks of Arbitrage Betting
While arbitrage is often described as "risk-free," several practical risks exist:
- Account restrictions and bans: Bookmakers actively identify arbers and limit or close their accounts. This is the most significant long-term challenge.
- Void bets: If one leg of your arb is voided (e.g., a player withdraws), you can be left with a one-sided position.
- Odds changes: If odds shift before you've placed both legs, the arb may disappear or become unprofitable.
- Human error: Inputting the wrong stake on a fast-moving opportunity can turn a profit into a loss.
- Withdrawal and deposit delays: Having funds spread across multiple accounts requires careful cash management.
Is Arbitrage Betting Legal?
Yes — arbitrage betting is entirely legal. It is, however, against the terms and conditions of most bookmakers, who reserve the right to limit or close accounts they identify as arbing. This is a commercial decision by the bookmaker, not a legal matter.
Is Arbitrage Right for You?
Arbing suits disciplined, methodical people who are comfortable managing multiple accounts, acting quickly, and handling the administrative demands of the strategy. It's not passive income — it requires time, software investment, and ongoing account management. For those willing to put in the work, it can be a low-risk way to generate returns, at least until accounts start to get restricted.