Arbitrage Calculator

How It Works

Using the arbitrage calculator is straightforward. Add each outcome by entering the best American odds you can find for that side (for example, +120 at one book and -110 at another). Enter your total stake, and the calculator will show you:

• Whether an arbitrage opportunity exists at those prices

• Return on Stake, the profit percentage you lock in

• Total Implied Probability across every outcome

• The exact stake to place on each side

You can add up to six outcomes for three-way and multi-way markets. The further the total implied probability drops below 100 percent, the larger your locked return.

Understanding Arbitrage Betting

An arbitrage bet works when the best available price for each outcome comes from different sportsbooks and those prices together imply less than 100 percent probability. For a two-way market, +120 on one side and -110 on the other add up to about 97.8 percent implied, which leaves a 2.2 percent margin. Split your stake in proportion to each outcome's implied probability and you return the same amount no matter which side wins.

The key thing to understand: a single sportsbook always prices both sides to add up to more than 100 percent, and that overage is the vig. Arbitrage only appears when two books disagree enough that their best prices, combined, dip under 100 percent. Those gaps are usually small, often one to three percent, so arbitrage is a volume game built on many small locked returns rather than one big score.

That margin is real but fragile. Lines move fast, and sportsbooks limit accounts they catch arbing, so the window to act is short. If you want to find these gaps at scale instead of by hand, our roundup of the best arbitrage betting tools covers the scanners built for it.

When to Use an Arbitrage Calculator

• Before placing an arb to confirm the combined odds actually clear a profit

• Sizing each leg so every outcome returns the same amount to the dollar

• Comparing a potential arb across books to see which pair of prices gives the best margin

• Checking three-way markets like soccer, where the stake split is harder to eyeball