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Arbitrage calculator

Two venues, two legs — and the fee line that decides whether the gap is real.

Check the live schedule — we do not assume one.

One pair is one YES contract and one NO contract.

The result appears below and the address bar becomes a link you can share.

Result

Locked profit per pair
3.00¢
Cost per pairBoth legs plus both fees
97.00¢
Fees per pair
2.00¢
Return on capital
3.09 %
Total for 100 pairsCapital tied up until resolution
$97.00
Total profit
$3.00

Riskless only if both legs fill at these prices and both venues resolve the question identically. Read both rulebooks — they are written separately.

The arithmetic is trivial. The execution is not.

If you can buy YES at 45¢ on one venue and NO at 50¢ on another, the pair costs 95¢ and exactly one of the two legs pays a dollar. The five cents is a lock — on paper. The reason people rarely collect it is that the calculation assumes both fills happen at those prices, at the same moment, in the size you want.

In practice the second leg moves while you are filling the first, the depth at the quoted price is a fraction of what you wanted, and a five-cent gap on the screen is a one-cent gap by the time you are done. That is not a flaw in the maths; it is the reason the gap existed.

Why the fees are inputs and not constants

This calculator asks you for the fees rather than assuming them. Venues revise their schedules — Polymarket US consolidated to a single coefficient in 2026, and any figure written into this page would be a confident false claim a quarter later. The live schedule at the venue is the only authority, and this is the one number that decides whether the gap is worth touching.

Two costs are not in this form and should be in your head: the spread you cross on each leg, and the capital tied up on both sides until the market resolves. A locked five cents that ties up 95¢ for eight months is a worse annualised return than it looks.

The resolution risk nobody prices

The two legs are on different venues, and different venues can resolve the same question differently. Their rules are written separately, their sources differ, and a disputed outcome does not have to be disputed the same way twice. A cross-venue arbitrage is only riskless if both contracts settle on identical criteria — read both rulebooks before you assume they do.

Common questions

How do I know if there is an arbitrage?

Add the YES price on one venue to the NO price on the other, plus both fees. If the total is below one dollar, the difference is locked in — assuming both legs actually fill at those prices and both venues resolve the question identically.

What fees should I enter?

Whatever the venue's live schedule says for your order. We deliberately do not preset one: fee schedules change, and a hardcoded number here would be wrong without warning.

Is cross-venue arbitrage actually riskless?

No. Execution risk means one leg can fill without the other, and resolution risk means two venues can settle the same question differently because their rules are written separately. The maths is riskless; the trade is not.

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These calculators do arithmetic on numbers you supply. They are not advice, and nothing here is a recommendation to take a position.