Free Sports Betting Arbitrage Calculator
Enter the odds for each side of a 2-way market in any format. The calculator finds the optimal stake split that guarantees the same return regardless of outcome — and tells you whether the odds actually form an arbitrage opportunity.
Leg 1 odds
Leg 2 odds
Stakes
How to use this calculator
Enter the odds for Leg 1 in any format — American, decimal, or fractional. The other two formats update automatically. Do the same for Leg 2.
Then enter any one of the three stake fields: total bankroll, leg 1 stake, or leg 2 stake. The calculator fills in the other two to produce an equal return on both outcomes. The results card shows whether the odds form a genuine arb, the guaranteed profit percentage, and the dollar profit at your chosen stake.
What is an arbitrage bet?
An arbitrage bet (also called a “sure bet” or “arb”) covers all outcomes of an event across different sportsbooks at odds that guarantee a profit regardless of the result. It works when different books price the same market differently, and the combined implied probabilities add up to less than 100%.
For example: Book A offers Team 1 at +145 (2.45) and Book B offers Team 2 at -130 (1.769). The implied probabilities are 40.8% + 56.5% = 97.3% — below 100%, meaning a 2.7% guaranteed profit is available.
How the stake split is calculated
The goal is to find stakes that return the same amount on both outcomes. In decimal odds, the formula for each leg is:
Stake = Total × (1 ÷ Leg Odds) ÷ (1/Odds1 + 1/Odds2)
This ensures that Stake1 × Odds1 = Stake2 × Odds2 = Total Return. The profit is the difference between Total Return and Total Stake.
When should you use this calculator?
Use it when you spot a potential arb manually or find one in our Arbitrage Finder. Enter the odds shown at each book to confirm the opportunity is genuine and to get the exact dollar amounts to bet at each book.
Always verify the odds at the sportsbook before placing your bets — lines can move in seconds, and a few cents difference can turn a profitable arb into a losing one.
Frequently asked questions
How does an arbitrage calculator work?▾
An arbitrage calculator takes the odds for each side of a market and finds the stake split that guarantees the same return regardless of which outcome wins. The key number is the sum of the implied probabilities: if 1/oddsA + 1/oddsB is less than 1 (i.e. the implied total is below 100%), a guaranteed profit is possible.
What is the formula for calculating arbitrage stakes?▾
In decimal odds, the optimal stake for each leg is: Stake = Total Bankroll × (1 ÷ Leg Odds) ÷ Arb Sum, where Arb Sum = 1/Odds1 + 1/Odds2. This ensures the payout from each outcome equals your bankroll divided by the arb sum.
How do I calculate guaranteed profit from an arbitrage bet?▾
Guaranteed profit = Total Stake × (1 ÷ Arb Sum − 1), where Arb Sum = 1/Odds1 + 1/Odds2. For example, if the arb sum is 0.979, profit = Total × (1/0.979 − 1) = Total × 0.0214, or about 2.14% of your total investment.
Can I enter a single leg stake instead of the total?▾
Yes. Enter any one of the three stake fields — total, leg 1, or leg 2 — and the other two will update automatically based on the odds you have entered.