Free calculator
Split a stake across an arbitrage window.
Enter a total stake and two or three decimal prices. The calculator sizes each branch for an equal return — and tells you whether the prices are an arbitrage at all before costs.
Outcomes
On paper only: fees, minimums, limits, and settlement-rule differences can remove the edge. Check the operator's accepted quote before staking.
How to read the result
An arbitrage stake split sizes each outcome's stake in proportion to its odds so every possible result returns the same amount, locking in a profit whenever the sum of the implied probabilities is below 100%.
Equal return, not equal stake. The split sizes each branch so every winning outcome returns the same gross amount. Higher prices get smaller stakes; the lowest price carries the largest share.
The implied total decides whether it is an arbitrage. Sum the reciprocal prices. Below 100%, the price set carries a theoretical edge; at or above 100%, there is no arbitrage on paper — the split is still shown so you can see why.
The edge dies in the details.Exchange fees, stake minimums, limits, and settlement-rule differences can all remove an on-paper arbitrage. Only the operator's accepted quote counts, and a window can close while you place the second leg.
For example: a €1,000 total stake split across two outcomes priced at 2.10 and 2.05 (implied total ≈ 96.4%) returns about €1,037 whichever outcome wins — a guaranteed profit of about €37, before fees.
Also see
De-vig / fair odds
Strip the bookmaker margin out of two- or three-way decimal prices and read the de-vigged fair odds and overround.
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Expected value
Compare your probability estimate against a price and see whether the bet has an edge — or a negative expectation.
Open calculator →
Kelly stake
Size a single bet against your bankroll with full or fractional Kelly, and see why the fraction exists.
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