Arbitrage Betting Calculator
Identifies guaranteed profit from arbitrage opportunities by computing the optimal stake split across two bookmakers offering opposing sides of the same market. Use it whenever combined implied probabilities sum to less than 100%.
Last updated: May 2026
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About this calculator
Arbitrage betting ('arbing') exploits discrepancies between bookmakers' odds so that all outcomes of an event are covered and risk-free profit is locked in. The arbitrage percentage for a two-way market is Arb% = (1/odds1) + (1/odds2), where odds are in decimal format. If Arb% < 1.00, a profit opportunity exists; the further below 1.00, the larger the margin. Guaranteed profit after commission: Profit = ((totalStake × (1 − commission/100)) / Arb%) − totalStake. Individual stakes per outcome are allocated proportionally to their implied probabilities: stake_on_i = totalStake × (1/odds_i) / Arb%. Variables: totalStake (total amount across both bets), odds1 and odds2 (decimal odds from each bookmaker), commission (exchange fee on net winnings, 0% for traditional books, 2–5% for exchanges). For a true arb, both bets must be placed at the stated odds before either book moves their line. Edge cases: arb opportunities typically last seconds to minutes before sharp books adjust; many books limit or close accounts that repeatedly arb against them; odds movement between placing the two bets (slippage) can collapse the margin to zero or negative. Exchange commission must always be deducted before calculating profit — overlooking it turns small arbs into break-even or losing positions. Three-way arbs (e.g., 1X2 soccer markets with draw) extend the formula to (1/odds1) + (1/draw_odds) + (1/odds2) and require three separate bets. Limits, max-bet rules, and stake reductions on suspected arbers all create execution risk that pure math doesn't capture.
How to use
Example 1: Bookmaker 1 offers 2.10 on Team A; Bookmaker 2 offers 2.05 on Team B. Total stake $1,000, commission 0%. Step 1: Arb% = (1/2.10) + (1/2.05) = 0.4762 + 0.4878 = 0.9640. Step 2: since 0.9640 < 1, an arb exists. Step 3: profit = ($1,000 × 1) / 0.9640 − $1,000 = $1,037.34 − $1,000 = $37.34. Step 4: stake Team A = $1,000 × 0.4762 / 0.9640 ≈ $494; stake Team B = $1,000 × 0.4878 / 0.9640 ≈ $506. Verify: $494 × 2.10 = $1,037.40, $506 × 2.05 = $1,037.30 — both return roughly $1,037 regardless of outcome, confirming the arb. Example 2: Same market with 3% exchange commission on the Team B side. Step 1: Arb% unchanged at 0.9640. Step 2: profit = (($1,000 × 0.97) / 0.9640) − $1,000 ≈ $1,006.22 − $1,000 = $6.22. Verify: a 3% commission ate 30 of the original $37 profit — illustrating why commission must always be modeled before declaring an arb.
Frequently asked questions
How do I find arbitrage betting opportunities between bookmakers?
Arbitrage opportunities arise when the combined implied probabilities across all outcomes from different bookmakers sum to less than 100%. Spot them by comparing odds on the same event across multiple sportsbooks and computing (1/odds1) + (1/odds2) — anything under 1.00 is an arb. Dedicated odds-comparison sites (OddsPortal, OddsJet, OddsMonkey) and arb-scanning software (RebelBetting, BetBurger, OddStorm) automate this process in real time, scanning hundreds of books simultaneously. Because bookmakers monitor for arbing and may limit or close accounts, many bettors use multiple accounts, place bets quickly before odds correct, and avoid round-number stakes that scream 'arber'. Long-running arb strategies are typically built around exchange arbing and Asian books with high limits.
What commission rate should I enter for betting exchange arbitrage?
Betting exchanges like Betfair and Smarkets charge commission on net winnings, typically 2–5% depending on account tier and market. Unlike traditional bookmakers who build margin into their odds, exchanges offer true market prices but deduct commission from your profits only (not losses). Enter the commission percentage your exchange charges in the Commission Rate field — the calculator adjusts the profit figure accordingly. Failing to account for commission can make what appears to be a profitable arb turn into a loss; many beginning arbers miss this and lose money on what looked like sure things. Betfair's commission tier system means heavy bettors pay lower commission, so factor in your tier when sizing your arb portfolio.
Why is arbitrage betting considered risk-free, and what are the real risks?
Arbitrage is mathematically risk-free in the sense that if all bets execute at the stated odds, every outcome yields a profit. Real-world risks include odds movement before all bets are placed (slippage), stake restrictions limiting how much a bookmaker will accept, account limitations or closures for suspected arbers, input errors (typo in stake or odds), and rule disputes if the event is voided by one book but settled by another (palpable error, abandoned games). There is also currency-exchange risk if the two books settle in different currencies. Execution speed and account health are therefore just as important as finding the arb in the first place. Most professional arbers accept a low-grade ongoing risk in exchange for the high-frequency small profits the strategy produces.
What are common mistakes when arbitrage betting?
Forgetting to subtract exchange commission turns marginal arbs into losers — the most common rookie error. Placing one side and waiting too long to place the other invites odds movement, creating an unhedged exposure. Mistaking palpable-error odds (bookmaker typo) for a real arb leads to voided bets and lost stake on the opposing side. Using round-number stakes ($100, $500) that flag your account as an arber accelerates restriction. Failing to read each bookmaker's rules for canceled games, voided markets, or in-play settlement differences creates risk where the math assumed none. Withdrawing too aggressively after each arb signals bonus-abuse behavior. Finally, not factoring in deposit/withdrawal fees (especially for international banking and crypto exchanges) can wipe out small arb margins entirely.
When should I NOT pursue arbitrage betting?
If your bankroll is small (under $1,000), bookmaker stake limits and minimum-stake requirements make arb profits trivial in dollar terms while the operational overhead (multiple accounts, fast execution, withdrawal management) remains the same. If your local laws restrict sports betting or arbitrage specifically (some jurisdictions do), pursuing it carries legal risk. If you can't open multiple bookmaker accounts (KYC restrictions, geo-blocks, banking limitations), arbing is impossible. If you have a tendency to chase losses or overthink — arbing requires discipline and adherence to a system, not gut decisions. If you cannot place both legs within a few seconds of each other (manual placement on slow connections), slippage will erode most of your profit. Finally, if you find an apparent arb with a margin above 3–5%, it is almost certainly a palpable error or a soft-bookmaker promotional misprice — verify with multiple sources before placing.