How do you calculate arbitrage?

Arb % = (1/Odds₁ + 1/Odds₂) × 100. If this is less than 100%, there's an arbitrage opportunity. Profit % = 100% - Arb %. Stakes are distributed proportionally to guarantee equal profit on each outcome.

Arbitrage Calculator

Find guaranteed profit opportunities by exploiting odds differences across sportsbooks.

Outcome 1 Odds

Best odds at Book A

Outcome 2 Odds

Best odds at Book B

Total Investment ($)

Total amount to invest

Arbitrage Status

Enter odds above

Check if arbitrage exists

Combined Implied Prob

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Guaranteed Profit

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ROI

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What is Arbitrage Betting?

Arbitrage betting (arbing, sure betting) exploits pricing inefficiencies between sportsbooks. When different books offer odds that don't add up to 100% probability, you can bet both sides and guarantee profit regardless of the outcome.

Arbitrage Check: (1/Odds₁ + 1/Odds₂) < 1

If the sum is less than 1 (or 100%), arbitrage exists

Arbs typically occur when books have different opinions on an event, or one book is slow to update lines after news breaks. They usually last minutes to hours before being corrected.

Example Calculation

Example: Lakers vs Celtics

DraftKings has Lakers at +155 (2.55 decimal)

FanDuel has Celtics at -140 (1.714 decimal)

Check for arb:
1/2.55 + 1/1.714 = 0.392 + 0.584 = 0.976

0.976 < 1.0 → Arbitrage exists!

Profit % = (1 - 0.976) × 100 = 2.4%

With $1,000 investment:
Stake Lakers: $1,000 × (0.392/0.976) = $401.64
Stake Celtics: $1,000 × (0.584/0.976) = $598.36

If Lakers win: $401.64 × 2.55 = $1,024.18
If Celtics win: $598.36 × 1.714 = $1,025.39

Guaranteed profit: ~$24-25 (2.4% ROI)

Risks & Considerations

⚠️ Arbitrage Is Not Risk-Free

While the math guarantees profit, practical risks exist: account limits/bans, line movement before placing both bets, maximum stake limits, and human error. Factor these into your strategy.

Account limiting: Sportsbooks track winners. Consistent arbing leads to bet limits or account closure.
Line movement: Odds can change between placing your first and second bet, turning a winner into a loser.
Max bet limits: You might not be able to place enough on one side to balance the arb.
Execution errors: Betting wrong game, wrong outcome, or wrong amount happens more than you'd think.
Palpable errors: Books can void bets if they claim an obvious pricing error.

How to Find Arbitrage Opportunities

Arb scanning software: OddsJam, RebelBetting, BetBurger scan dozens of books for live arbs.
Line shopping manually: Compare odds across books for the same market.
New sportsbook promos: Boosted odds on new books often create arbs against sharp lines.
Live betting: In-play odds can diverge significantly — fast execution required.
3+ way markets: Soccer, tennis with retirement, etc. have more arb potential due to more outcomes.

Frequently Asked Questions

Is arbitrage betting legal?

Yes, completely legal. You're just taking the best available odds at different books. However, sportsbooks reserve the right to limit or close accounts, and many will if they detect consistent arbing.

How much can you realistically make?

Arbs typically yield 1-5% per opportunity. With $10,000 bankroll finding 5 arbs/day at 2% average, that's ~$1,000/day turnover for $20/day profit. The limiting factor is usually account limits, not opportunities.

What's the best book for arbing?

You need both sharp books (Pinnacle, Circa) for accurate lines and soft books (FanDuel, DraftKings) for boosted odds. Pinnacle rarely limits but also rarely offers arbs. Soft books offer arbs but limit quickly.

Should I arb or just bet +EV?

Different strategies. Arbing is lower variance but lower profit and causes faster limiting. +EV betting has higher variance but potentially higher long-term profits and can be sustained longer by looking recreational.