Arbitrage betting (commonly called "arbing") exploits pricing differences between bookmakers to guarantee a risk-free profit by covering all possible outcomes of an event. When Bookmaker A prices Outcome X higher than Bookmaker B, and Bookmaker B prices Outcome Y higher than Bookmaker A, it may be possible to back both at a combined implied probability below 100% — locking in profit.
The mathematics behind arbitrage are straightforward. If the sum of implied probabilities across all outcomes is less than 1 (or 100%), an arbitrage exists. For example, if Bookmaker A offers Team X to win at 2.10 (implied probability 47.6%) and Bookmaker B offers Team Y to win at 2.10 (47.6%), the combined probability is 95.2% — leaving a 4.8% guaranteed profit margin.
Execution requires acting quickly. Prices change rapidly, and an arb that existed when you discovered it may be gone by the time you place the second leg. Many arbitrage bettors use specialist software or odds comparison services that flag opportunities in real time and calculate the exact stakes to place on each outcome.
The main practical obstacle is account longevity. Bookmakers actively monitor for arbing patterns and will reduce maximum bet stakes (known as "gubbing") or close accounts. For this reason, many arbitrage bettors cycle through promotional accounts, use multiple identities (which is against bookmaker terms), or operate through betting exchanges that cannot restrict winners.
Example
England vs France. Bookmaker A offers England at 2.20; Bookmaker B offers France at 2.30; Bookmaker C offers Draw at 3.60. Total implied probability = (1/2.20) + (1/2.30) + (1/3.60) = 45.5% + 43.5% + 27.8% = 96.8%. Stake £321 on England, £304 on France, and £194 on the Draw (total £819). All three outcomes return approximately £706 — but wait, that is less than the total staked. Adjust the calculation: if combined implied probability is below 100%, profit is guaranteed; if above 100% (as here), no arb exists.