Arbitrage betting, also known as surebetting or arbing, is a strategy that exploits price discrepancies between different bookmakers to guarantee a profit regardless of the outcome. The technique is borrowed from financial arbitrage and relies on the same principle: simultaneously buying and selling equivalent positions at different prices.

An arbitrage opportunity arises when the combined implied probabilities offered by different bookmakers for all outcomes of an event sum to less than 100%. For example, if Bookmaker A offers Team X at decimal odds of 2.20 and Bookmaker B offers Team Y at 2.10 in a two-outcome market, the combined implied probability is (1/2.20 + 1/2.10) = 45.5% + 47.6% = 93.1%. The remaining 6.9% represents the arbitrage margin, which can be locked in as guaranteed profit by distributing the stake proportionally across both outcomes.

The stake calculation for each leg of an arbitrage bet follows a specific formula: individual stake equals (total investment × implied probability of that outcome) divided by the sum of all implied probabilities. Precise calculation is critical because even small rounding errors can eliminate the narrow margins involved.

In practice, arbitrage betting faces significant constraints. Bookmakers actively monitor for arbing behavior and may limit or close accounts. Odds can shift between placing the first and second legs. Transaction costs, currency conversion fees, and withdrawal delays can erode margins. Despite these challenges, the mathematical foundation remains sound and is studied in both gambling theory and financial mathematics.

Bettors evaluating potential arbitrage opportunities can use a surebet calculator to determine optimal stake distribution and verify whether a genuine arbitrage exists before committing funds.