Arbitrage calculator
An arbitrage is when the best prices for every outcome, taken at different bookmakers, add up to less than 100% implied probability — so the right stakes return the same amount whatever the result, as long as every bet stands at those odds.
Updated 19 October 2026 · Free, no sign-up. All calculations run in your browser. 18+ · Play responsibly.
How it works
- Enter the best price for each outcome, each from the bookmaker that offers it.
- Enter how much you want to put in overall.
- The calculator splits the stake in proportion to 1 ÷ odds, so every outcome pays back the same amount.
The formula
Arbitrage exists when 1/odds₁ + 1/odds₂ (+ 1/odds₃) < 1
Stake on outcome i = Total × (1/oddsᵢ) ÷ Σ(1/odds) · Return = Total ÷ Σ(1/odds)
Worked example
Bookmaker A pays 2.10 on the home side and bookmaker B pays 2.05 on the away side of a two-way market. 1/2.10 + 1/2.05 = 0.4762 + 0.4878 = 0.9640, which is 96.40%: an arbitrage of 3.6%. With €100 in total you stake €49.40 on home and €50.60 on away; either result returns €103.73, a profit of €3.73.
The risks
The maths is fixed, but an arbitrage only pays if every bet is accepted and settled at the odds you entered:
- Odds change: a price can move between your first and your last bet. Place first at the bookmaker most likely to change, and check the profit again before the second bet.
- Stake limits: a bookmaker may accept only part of your stake, which leaves the other side unbalanced.
- Voided or cancelled bets: bookmakers can void bets on prices they call an obvious error (“palpable error”), or when a match is postponed or abandoned — the other bet still stands.
- Different rules: both bets must settle the same way (90 minutes vs. extra time, void and dead-heat rules).
- Commission and fees: exchange commission (e.g. Betfair) or payment fees reduce the return — enter net odds.
- Account restrictions: bookmakers may limit accounts that bet this way.
FAQ
Is arbitrage risk-free?
No. The calculation is exact, but odds changes, stake limits and voided bets can leave one side unmatched. Check every bet is accepted before you count the profit.
Is arbitrage betting legal?
Yes, placing bets at different bookmakers is legal. Bookmakers can still limit accounts that bet this way, so many bettors use arbitrage alongside value betting.
Why is the profit so small?
Real arbitrage gaps are usually 1–4%. The profit comes from repeating it, not from one bet.