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Arbitrage Calculator
Compare cross-book prices, calculate a stake split across legs, and see the return implied by the entered prices if every outcome is covered, before fees and the risk of sportsbook limits. Two-way and N-way markets supported.
Arbitrage Calculator
Check 2-way, 3-way, or N-way prices for true arbitrage. Add as many legs as the market needs and label each book for tracking.
Math is exact. Execution risk (stake limits, voids, palpable errors, slow lines) is what determines realized edge.
When implied probabilities sum below 100%, you have an arb
A normal vigged market has implied probabilities summing to 104-110% — the overround is the
book's margin. Two different books can disagree on the underlying probability enough that the
cheapest cross-book combination sums to less than 100%. The return percentage is (1 / implied_sum - 1) × 100, using the implied sum as a decimal, provided the
bets cover every outcome, exactly one wins, and the prices hold. A combined implied sum of 96%
gives (1 / 0.96 - 1) × 100 = 4.17% ROI on the total wager under those assumptions,
before fees.
Stake split: solve for equal payout
The arbitrage stake split is proportional to implied probability: stake_i = total × (implied_i / implied_sum). This makes the total payout match
the others, whichever leg wins. Equal-dollar splits do not achieve this — the favored
side pays out less and turns the arbitrage back into a regular bet with risk.
Worked example: +110 / +110 cross-book
Book A: +110 implied 47.62%. Book B opposite side: +110 implied 47.62%. Sum = 95.24%. With $100 total stake, split is $50.00 on each side. Each leg returns 50 × 2.10 = $105.00 on win, $0 on loss — exactly $105 returned whichever side wins. Profit: $5.00 (5.00% ROI), if both prices still hold when you place the bets. Real-world arbs are rarely this clean and usually 1-3% ROI, but the math scales identically.
FAQ
What is arbitrage betting (a "surebet")?
Arbitrage betting means staking on every outcome of a market across two or more sportsbooks at prices that lock in a profit, as long as the bets cover every possible outcome, exactly one outcome wins, and the prices and limits hold when you place the bets. When the cross-book implied probabilities sum to less than 100%, the return percentage is (1 / implied_sum - 1) × 100, using the implied sum as a decimal, if all of that holds. Real arbs are rare, small (usually 1-4% return), and short-lived — books move lines or limit accounts as soon as one side gets hit. The math is risk-free only if those conditions hold; the execution rarely is.
How do I know if a two-book line spread creates an arbitrage opportunity?
Sum the implied probabilities of both sides across the books you have access to. If the sum is less than 100% (1.00 in decimal terms), an arb exists. For example: Book A offers Team Home +105 (implied 48.78%) and Book B offers Team Away +110 (implied 47.62%). Sum = 96.40%. Stake split proportional to implieds across $100 total: $50.60 on home, $49.40 on away. Either side wins; total payout is $103.74 — a $3.74 profit (3.74% ROI) if both prices still hold when you place the bets.
How are stakes split between books?
The split solves for equal payout regardless of which side wins. The formula is stake_i = total_stake × (implied_prob_i / implied_sum). Each leg's stake share is proportional to its implied probability, so both legs return the same total amount. If you stake equally instead, one outcome pays out more than the other and you stop being arbitraged on one side. The calculator handles the split automatically — paste the prices, set the total stake, get the per-book amounts.
What are the real risks of arbitrage betting?
Several. (1) Limits — books limit consistently arbed accounts within weeks. (2) Line moves — by the time you place the second leg, the price might have moved and the arb is gone. (3) Voids and pushes — if one book voids or pushes a leg, the other side becomes a single open bet (often -EV). (4) Account closures — sportsbooks identify arbers via betting patterns and close accounts. (5) Bonus restrictions — promo terms often exclude arb-eligible markets. Real arbing requires multiple funded accounts, fast execution, and tolerance for declining account quality.
How is arbitrage different from a middle or a hedge?
Arbitrage: bet ALL outcomes simultaneously across books for the same return whichever outcome wins, if the prices hold when you place the bets. Middle: bet OPPOSING sides at different lines, hoping the result lands between them so both win — both bets can lose if the result lands outside the corridor. Hedge: take a SECOND bet AFTER placing the first to reduce variance on an already-open position; it trades EV for variance reduction and is rarely zero-risk. Arbing is the only one of the three that is zero-risk on paper, and only when the bets cover every outcome and the prices hold; the others involve real downside.
Devig a market to find the fair-price baseline that arbs deviate from.
Compare the calculated payouts for an open ticket and an opposing position, instead of placing both sides simultaneously.
Apply the same stake-split math to convert a free bet into cash.