Betfair Arbitrage Calculator — Find Risk-Free Profit

Arbitrage (Arb) Calculator

Check whether two opposing prices create a risk-free profit opportunity (combined implied probability under 100%).

How to Use:

Total stake — amount to spread across both outcomes.
Outcome A / B odds — e.g. bookmaker back vs exchange lay.
Add commission if one leg is on Betfair.

Real arbs are rare and short-lived. Always confirm prices and stake limits before betting.

Find stakes for a guaranteed profit on two opposing outcomes.

Fixed Total Stake (£): Outcome A Odds: Outcome B Odds: Commission rate (%):

Applied to gross profit. Set 0 if neither leg has exchange commission.

Arbitrage Summary

Combined Percentage:

Profit Margin:

Status:

Stake on A:

Stake on B:

Total Stakes:

Guaranteed Profit:

When to use this calculator

Use the arbitrage finder when you have prices from two sources (e.g. a bookmaker back price and a Betfair lay price) and want to check if a risk-free profit exists. Enter both odds and the calculator shows whether the combined implied probability is under 100%.

Note: real arb opportunities are rare, short-lived, and may not account for commission or stake limits.

Frequently asked questions

What is a betting arbitrage opportunity?

Arbitrage exists when you can back and lay (or back at multiple books) such that you profit regardless of the outcome. The combined implied probability must be below 100%.

Why are arbs hard to find on Betfair?

Markets are efficient, commission reduces margins, and odds move quickly. Most arbs last seconds and require automation.

Does this calculator include commission?

Check commission separately with the exchange commission calculator. Even a small arb can disappear after 5% commission.

Disclaimer: For educational and planning purposes only. Not financial or betting advice. 18+ · BeGambleAware.org