Arbitrage Calculator
Enter American odds for both sides of a 2-way market across two sportsbooks. The calculator detects whether the prices form a true arbitrage (surebet), the optimal stake distribution, and your guaranteed profit margin.
Adjust inputs above. Combined implied probability under 100% means the market is an arb.
How to actually find arbitrage opportunities
True 2-way arbitrage at major US sportsbooks is rare. The combined implied probability of both sides usually sums to 102-108% (the operator margin). Pure arbs appear only when:
- Two operators update lines at different speeds after news (player out, weather change)
- One operator has a promotional boost (e.g. "+25% on this team") that pushes the price beyond fair
- Operators disagree about pricing on niche markets (lower-tier sports, alternate lines)
Real-time arbitrage scanners (RebelBetting, OddsJam) cost $50-150/month and find dozens of opportunities daily. Manual arbitrage finding is nearly impossible at scale because opportunities last 1-5 minutes before being arbed-out.
Risk warning: sportsbooks aggressively limit and close accounts they identify as arbing. Most arbers extend account lifespan to 50-200 bets before limits drop to unusable levels. Treat arbitrage as a short-term cash-extraction strategy, not a sustainable income.
Frequently Asked Questions About Arbitrage
What is arbitrage betting (arbing)?
Arbitrage betting means placing bets on all possible outcomes of a market across different sportsbooks, where the combined prices are mispriced enough that you guarantee profit regardless of outcome. The total implied probability across both sides sums to less than 100%; the gap is your guaranteed profit margin.
Is arbitrage betting legal in the US?
Yes, arbitrage is legal in every state with legal sports betting. However, sportsbooks may close or limit accounts they identify as arbing. Most major US operators detect arbing within 50-100 bets via pattern analysis (small irregular stakes, paired with opposing bets at competitor books).
How big are typical arbitrage profits?
Pure arbitrage opportunities at major US books are rare and small (1-3% per attempt). They appear briefly when one operator is slow to update lines after news. Specialized arbitrage scanners can find them in real-time but most opportunities last under 5 minutes before lines move.
How is the arbitrage stake calculated?
For a 2-way market: stake on each side = (total bankroll) × (implied prob of opposite side / sum of implied probabilities). The calculator does this for you. Profit on each outcome should be equal (within rounding).
What can go wrong with arbitrage?
Three big risks: (1) one leg gets cancelled or void (e.g. player scratched), leaving you exposed on the other side, (2) execution delay between placing the two bets allows the line to move against you, (3) operator account limits or closures eliminate your ability to place future arbs. Manage all three carefully.