Surebet (Arbitrage) Calculator

A surebet on two outcomes

Two-way markets — tennis, the money line, over/under, any handicap with no draw — are where most arbs are found, because there is nothing to cover but the two sides. Add 1 ÷ odds for each: 2.10 and 2.10 give 0.476 + 0.476 = 0.952, so the pair returns 1 ÷ 0.952 = 1.050 per unit and locks 5%.

Split the budget in the same proportion as those implied probabilities and both sides return the identical amount. At equal prices that is half each; at 3.20 against 1.50 it is 32% on the favourite's opponent and 68% on the favourite. Enter two prices above and the two stakes appear.

A surebet on three outcomes

Football's 1X2 market adds the draw, so the arithmetic runs over three prices instead of two and the sum has to clear a third leg's margin. That makes three-way arbs rarer and usually thinner — and it means the draw price, the one most bettors ignore, is where the opportunity normally hides.

Nothing else changes: the calculator takes any number of prices, so paste all three and it returns the three stakes, the guaranteed return and the margin. The catch is execution — three bets across three books take longer to place, and the first price often moves before the last one is on.

When does an arbitrage exist?

Each price implies a probability of 1 ÷ odds. Add the implied probabilities for every outcome of the same event: if the total comes to less than 100%, an arbitrage exists. That happens when two bookmakers disagree enough — one is generous on the home side, another on the away side — to cover the whole market with room to spare.

The further below 100% the sum sits, the bigger the guaranteed margin. Real arbs are usually small (0.5–3%) and disappear quickly as books adjust their lines.

How to split the stake

Stake on each outcome in proportion to its implied probability: stake = total × (1 ÷ odds) ÷ sum-of-implied. Done correctly, every outcome returns exactly the same amount — your total stake divided by that sum — so the profit is identical whoever wins.

Enter the odds from each bookmaker and your total budget; the calculator returns the exact stake for each side, the guaranteed return and the profit in money and percent.

The risks behind a guaranteed profit

Arbitrage is mathematically risk-free but practically fragile: odds move while you place the second leg, limits and bet cancellation are real, and books restrict accounts that arb consistently. Treat the calculator's profit as the best case if both bets land at the quoted prices.