How arbitrage works
When two books price the same market differently enough, the combined no-vig probabilities dip below 100 percent, creating an arb. You stake each outcome at the book offering the best price, in amounts sized so every result returns more than your total outlay. The profit is small, often 1 to 3 percent, but it is locked in the moment both bets are placed.
A worked example
Book A has Team X at +105 and Book B has Team Y at +105 in a two-way market. Staking both sides in the right proportion returns a profit whichever team wins. An arbitrage calculator takes the two prices and your total stake and outputs exactly how much to put on each side to guarantee the return.
The catch
Arbs vanish fast as lines move, require accounts and balances at multiple books, and books limit or restrict bettors who arb aggressively. The margins are thin and the operational effort is high. For most bettors, hunting positive expected value and always taking the best number is a more durable edge than chasing fleeting arbs.
Frequently asked questions
Is arbitrage betting legal?
Betting the same event at multiple regulated books is legal, but books may limit or close accounts of bettors who arbitrage regularly. It is against no law, only against the book's interest.
How much can you make arbitrage betting?
Individual arbs usually return 1 to 3 percent. The gains are small and require significant capital across books, and opportunities disappear quickly.
Related terms
21+. For entertainment and educational purposes, not financial advice. If gambling stops being fun, take a break. 1-800-GAMBLER. Regulated US books only.