What is arbitrage betting?
Arbitrage betting — "arbing" or a "sure bet" — means betting every outcome of a market at different sportsbooks when the prices are mismatched. When the combined implied probability falls below 100%, you can split a stake so you profit regardless of the result.
Worked example
Book A prices Team X at +120; Book B prices Team Y at +105. You stake $200 total.
Decimal odds: 2.20 and 2.05.
1÷2.20 + 1÷2.05 = 0.4545 + 0.4878 = 0.9423 — below 1, so an arb exists.
Stake on X = $200 × 0.4545 ÷ 0.9423 = $96.49; stake on Y = $103.51.
Result: either outcome returns about $212.26 — a guaranteed $12.26 profit (6.1%).
Frequently asked questions
Is arbitrage betting legal?
Yes, it is legal. However, sportsbooks dislike it and may limit stakes or close the accounts of bettors they identify as arbers.
How often do arbitrage opportunities appear?
They are uncommon and short-lived. Odds move quickly, so most arbs exist for only a few minutes.
Why did the calculator say no arbitrage?
If the two prices add up to 100% implied probability or more, there is no edge — betting both sides would guarantee a small loss instead of a profit.