Arbitrage Betting: What It Is and How Bettors Use It
Arbitrage betting, commonly called "arb betting," is one of the few strategies in sports betting that offers a mathematically guaranteed profit. It requires no prediction about who will win. Instead, it exploits pricing differences between sportsbooks to cover every possible outcome of an event at favorable odds. Done correctly, you profit regardless of the result.
This guide breaks down how arbitrage betting works, how to find opportunities, and what you need to know before you start.
How Arbitrage Betting Works
Sportsbooks set their own odds independently. Because of this, two books will sometimes price the same game differently enough that you can bet both sides and guarantee a return. The signal to look for is a combined implied probability across all outcomes that falls below 100%.
In a standard market, the juice baked into the odds pushes the combined implied probability above 100%. That overage is the sportsbook's margin. An arb opportunity exists when you find two books where the combined implied probability falls below 100%, meaning the market is mispriced across those books.
Implied Probability Quick Recap
To evaluate any arb, you need to convert odds to implied probability. For American odds:
- Positive odds (like +150): implied probability = 100 / (odds + 100)
- Negative odds (like -130): implied probability = |odds| / (|odds| + 100)
If you want to move quickly between formats, use the Odds Converter to avoid manual math under time pressure.
A Simple Arbitrage Betting Example
Say two sportsbooks are offering different prices on the same tennis match:
- Book A has Player 1 at +120
- Book B has Player 2 at +115
Calculate the implied probabilities:
- Player 1 at +120: 100 / (120 + 100) = 45.5%
- Player 2 at +115: 100 / (115 + 100) = 46.5%
Combined: 45.5% + 46.5% = 92%
That is 8 percentage points below 100%, which confirms an arb exists. If you allocate your total stake correctly across both bets, you lock in a profit of roughly 8% regardless of who wins.
To figure out exact stake sizing, plug the numbers into the Arbitrage Calculator. It will tell you how much to bet on each side to guarantee an equal return.
Two-Way vs. Three-Way Arbs
Most arb opportunities fall into two categories:
Two-Way Arbs
These apply to markets with two outcomes, such as moneylines in football, basketball, tennis, or UFC. You cover both sides across two different books. This is the most common type and the easiest to execute.
Three-Way Arbs
These come up in soccer and other sports where a draw is a separate outcome. You need to cover all three results (home win, draw, away win) across books. Three-way arbs are harder to find and trickier to execute because you are managing three bets across potentially different time windows.
How to Find Arb Opportunities
Finding arbs manually is slow. Odds move fast, and a line change at one book can eliminate an opportunity within minutes. Here is how serious arb bettors approach it:
Use an odds comparison tool. Platforms that display live odds from multiple sportsbooks side by side make it much easier to spot discrepancies. The Line Whale homepage shows live odds across books for major sports, giving you a real-time view of where prices diverge.
Focus on less liquid markets. Big markets like NFL point spreads get corrected quickly. Smaller markets like player props, second-half lines, or lower-tier leagues tend to hold pricing gaps longer.
Act fast. Arb windows are short. A line can shift within seconds of a sharp bet or a news update. You need accounts funded and ready at multiple sportsbooks before you start hunting.
Use more books. The more sportsbooks you have access to, the more arbs you will find. Cross-referencing several books dramatically increases your chances of spotting a gap. The Sportsbook Rankings page identifies which books are most competitive in the markets you want to target.
Risks and Limitations
Arb betting offers a theoretical guarantee, but there are real practical hurdles.
Account restrictions. Sportsbooks do not like arb bettors. If you consistently beat the closing line or show obvious arbing patterns, books will reduce your bet limits or close your account entirely. This is the biggest long-term threat to any arb operation.
Line movement risk. If you place one side of an arb and the other book moves the line before you get the second bet down, you are left with a one-sided position. This exposure can result in a loss and is the most common execution risk arb bettors face.
Funding logistics. You need capital spread across multiple sportsbooks at all times. Moving money between accounts has friction, and locked-up funds limit your flexibility.
Small margins. Most arbs return 1% to 5%. You need significant volume and stake sizes for the profits to be meaningful.
Arb Betting vs. Hedging
These two strategies are related but distinct. Hedging means placing a second bet to reduce risk on a position you already hold, often to lock in profit after a line moves in your favor. Arbing means entering both sides simultaneously with guaranteed profit built in from the start.
If you have a futures bet running and want to lock in winnings before the event concludes, that is a hedging scenario. The Hedging Calculator handles that math for you.
Is Arbitrage Betting Legal?
Yes. Arb betting is completely legal in the US. There is no law or regulation against placing bets at multiple sportsbooks and covering different outcomes. Sportsbooks may limit your account if they identify the pattern, but the practice itself is not illegal.
Key Takeaways
- Arbitrage betting exploits odds discrepancies between sportsbooks to guarantee a profit on every outcome.
- An arb exists when the combined implied probability across all outcomes falls below 100%.
- Two-way arbs are more common and easier to execute than three-way arbs.
- Speed matters. Arb windows close quickly as books adjust their lines.
- Proper stake sizing is essential. Use a calculator to allocate correctly across both sides.
- Account longevity is a real concern. Sportsbooks limit or close accounts showing arbing patterns.
- Margins are small. High volume and disciplined bankroll management are necessary to make arbing worthwhile.