A sure bet — also called an arbitrage bet — is a set of wagers that guarantees profit regardless of the result. It happens when different bookmakers disagree enough on the odds that you can back every outcome and still come out ahead.

The classic setup is a two-way market: Bookmaker A offers 2.10 on Team X while Bookmaker B offers 2.10 on Team Y. Betting the right amounts on both locks in about 4.8% profit before you even know the score.

The hard part is the math. You must split your total stake in exact proportion to the odds, and a small error wipes out the edge. That is why serious arbers never do it by hand.

Three-way markets (common in football) work the same way with one extra leg. Opportunities usually last minutes because odds move fast, so having the calculation ready before you spot the gap is what separates profit from missed chances.