Find and exploit odds discrepancies across sportsbooks with the PromoGrind Arbitrage Calculator — calculate exact stakes to lock in a guaranteed profit on any 2-way or 3-way market.
Arbitrage betting — commonly called arbing or sure betting — exploits pricing disagreements between sportsbooks. When Book A prices Team X at +150 and Book B prices their opponent at +175, the combined implied probability of both outcomes can fall below 100%. By betting on both sides at the right stakes, you guarantee a profit no matter which team wins.
Every sportsbook builds a margin (vig) into their odds so the implied probabilities of all outcomes add up to more than 100%. Arb opportunities emerge when different books shade their lines in opposite directions — for example, one book is heavy on the home team and another is heavy on the away team. The arbitrage calculator divides your target stake between both sides proportionally, ensuring each outcome covers the other's loss and leaves a net profit.
A margin percentage above 1% ROI is generally worth pursuing. Opportunities between 2% and 5% are excellent. Anything above 5% should be double-checked for errors or line movement. The calculator shows you the arb percentage instantly — if it is positive, you have a profit-guaranteed opportunity.
A 2-way arb covers markets with exactly two outcomes (spread, moneyline in most US sports). A 3-way arb covers markets that include a draw (soccer, hockey moneylines). Three-way arbs require stakes on three outcomes and are less common but can appear in soccer and international markets. PromoGrind supports both formats.