Arbitrage Calculator

How the arbitrage works

If you buy the Yes contract and the No contract for the same event, exactly one of them settles at $1. So whenever the two prices add up to less than $1.00, you can buy both and lock in the difference no matter the outcome. The calculator splits your budget so you hold the same number of each contract — that is what makes the return identical either way — and shows the guaranteed profit. If the combined price is $1.00 or more, there is no arbitrage.

Why it is harder than it looks

The gaps are usually small and short-lived, and several frictions can wipe them out: fees on both legs, liquidity limits on how much you can fill, timing as prices move while you execute, and — most dangerous — resolution differences if two venues word the same market slightly differently. Always net out fees first and read both sets of resolution criteria. The full method is in our guide to arbitrage and no-vig trading.

Capturing cross-venue arbs means holding accounts on more than one platform — see Kalshi vs Polymarket and the full platform reviews. To strip the margin from sportsbook-style odds, use the no-vig calculator.

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Frequently asked questions

How does prediction market arbitrage work?

If you buy both the Yes and No contracts for the same event, exactly one settles at $1. Whenever the two prices add up to less than $1.00, buying both locks in the difference as guaranteed profit, whatever the outcome.

Is arbitrage really risk-free?

In theory the profit is locked, but in practice fees, liquidity limits, timing and — most dangerously — differing resolution rules across venues can erase or reverse the edge. Always net out fees and read both sets of resolution criteria first.

Why do I need accounts on two platforms?

Cross-venue arbitrage exists because the same market is priced differently on different exchanges. To buy each side where it is cheapest, you need a funded account on more than one platform.