Arbitrage Calculator

What is arbitrage betting?

Arbitrage (or “arbing”) is backing every possible outcome of an event across different bookmakers so that your total return is larger than your total stake — whatever the result. It works because books disagree on prices. When one is generous on the favourite and another is generous on the underdog, the combined market can add up to less than 100%, and the gap is yours to keep.

The math behind it

Convert each price to its implied probability by taking 1 ÷ decimal odds, then add them up. We call this the inverse sum (the combined book):

• Inverse sum = 1/A + 1/B. If this is below 1.00, an arbitrage exists.
• Stake on A = total × (1/A) ÷ inverse sum — and the same for B. This splits your money so both outcomes pay back the same amount.
• Guaranteed return = total ÷ inverse sum.Subtract your stake and that’s your locked-in profit.

Example: Book A prices one side at 2.10 and Book B prices the other at 2.05. The inverse sum is 1/2.10 + 1/2.05 ≈ 0.964 — under 1.00, so staking $100 returns about $103.70 regardless of the result. A small edge, but a real one.

Why it’s harder than it looks

Arbitrage is real, but the edges are thin and they vanish fast. Prices move the moment you go to place the second leg, books limit or close accounts that only ever take arbs, and a fat-fingered stake or a voided bet can turn a sure thing into a loss. The numbers below are illustrative — they assume you get both legs down at the prices shown.

How Winora helps

Doing this by hand across dozens of books is a full-time job. Winora scans thousands of lines a second and posts live arbitrage and positive-EV opportunities straight to your Discord — already devigged, with the stake split worked out for you.