Arbitrage Betting Calculator
Identify guaranteed profit from arbitrage opportunities by calculating the optimal stake split across two bookmakers. Use it whenever two books offer odds that together imply less than 100% probability.
About this calculator
Arbitrage betting (or 'arbing') exploits discrepancies between bookmakers' odds so that all outcomes are covered and a risk-free profit is locked in. The arbitrage percentage is calculated as: Arb% = (1 / odds1) + (1 / odds2). If Arb% < 1, a profit opportunity exists. The guaranteed profit after commission is: Profit = ((totalStake × (1 − commission / 100)) / Arb%) − totalStake. Individual stakes per outcome are allocated proportionally to their implied probabilities: stake on outcome i = totalStake × (1 / oddsI) / Arb%. The commission term accounts for exchanges like Betfair that charge a percentage on winnings. A smaller Arb% means a larger profit margin. Arb opportunities are typically short-lived as bookmakers adjust their lines quickly.
How to use
Example: Bookmaker 1 offers odds of 2.10 on Team A; Bookmaker 2 offers 2.05 on Team B. Total stake: $1,000, commission: 0%. Step 1: Arb% = (1 / 2.10) + (1 / 2.05) = 0.4762 + 0.4878 = 0.9640. Step 2: Since 0.964 < 1, an arb exists. Step 3: Profit = ((1,000 × 1) / 0.964) − 1,000 = $1,037.34 − $1,000 = $37.34 guaranteed profit. Step 4: Stake on Team A = 1,000 × 0.4762 / 0.964 ≈ $494; Stake on Team B ≈ $506.
Frequently asked questions
How do I find arbitrage betting opportunities between bookmakers?
Arbitrage opportunities arise when the combined implied probabilities across all outcomes from different bookmakers sum to less than 100%. You can spot them by comparing odds on the same event across multiple sportsbooks and calculating (1/odds1) + (1/odds2). Dedicated odds-comparison sites and arb-scanning software automate this process in real time. Because bookmakers monitor for arbing and may limit or close accounts, many bettors use multiple accounts and place bets quickly before odds are corrected.
What commission rate should I enter for betting exchange arbitrage?
Betting exchanges like Betfair and Smarkets charge a commission on net winnings, typically between 2% and 5% depending on your account tier and market. Unlike traditional bookmakers who build margin into their odds, exchanges offer true market prices but deduct commission from profits only. Enter the commission percentage your exchange charges in the Commission Rate field — the calculator adjusts the profit figure accordingly. Failing to account for commission can make what appears to be a profitable arb turn into a loss.
Why is arbitrage betting considered risk-free and what are the real risks involved?
Arbitrage betting is mathematically risk-free in the sense that if all bets are placed at the stated odds, every outcome yields a profit. However, real-world risks include odds movement before all bets are placed, stake restrictions limiting how much a bookmaker will accept, and account limitations or closures for suspected arbers. There is also the risk of input errors — entering the wrong stake or odds can turn a profit into a loss. Execution speed and account health are therefore just as important as finding the arb in the first place.