Free arbitrage betting calculator. Enter odds from two books to detect an arb and get the precise stake split for a guaranteed, risk-free profit.
An arbitrage exists when you can back every outcome at prices good enough that the total staked profits no matter what happens — it occurs when the implied probabilities across the best prices add up to under 100%. Because one book builds in a margin, arbs almost always need lines from two books that disagree.
Arbs are real but thin, short-lived, and quickly limited by books. Treat this as an education tool. A steadier edge comes from beating the closing line.
Convert each side to decimal odds, take the reciprocal of each (implied probability), and split your total stake in proportion to those reciprocals. If they sum to under 1, every outcome returns the same profit.
Betting arbitrage is legal where betting is legal, but books discourage it and will limit accounts. Nothing here is betting advice.