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Prediction markets

Compare prediction market prices

The same question is priced differently on every platform. OddsGrab lines them up side-by-side so you can see who is cheapest, how wide the spread is, and where to back each side — the OddsChecker for prediction markets.

A contract pays $1 if it resolves Yes, so its price in cents is the implied probability. Backing a side for less means a bigger payout — the cheapest price wins, exactly like shopping the best line at a sportsbook.

Politics Closes in 129 days · $6.4M volume

Republicans win 2026 House majority

Control of the U.S. House after the November midterms.

Best price: 58¢ on Polymarket — 3¢ cheaper than Kalshi at 61¢. That gap is the cross-platform edge.

Platform “Yes” price Compare
Polymarket Best 58¢ Compare on Polymarket ↗
PredictIt 59¢ Compare on PredictIt ↗
Kalshi 61¢ Compare on Kalshi ↗
Manifold Markets signal 55¢ Signal only

● highlights the cheapest tradeable price to back “Yes.” Prices in cents = implied probability. Demo data — see the full market →

Why prices differ across platforms

If every venue priced the same question identically there would be nothing to shop. They don’t — and four forces explain the gap.

Liquidity

A market with millions in volume prices tightly; a thin one drifts. Where order books are shallow, a single trade can move the price several cents — so the same question can sit a nickel apart across venues.

Fees & funding

Trading fees, withdrawal costs, and how you fund (USDC on Polymarket vs. a US bank on Kalshi) all get priced in. A platform that charges more to settle tends to quote slightly worse to compensate.

User base

Each venue draws a different crowd — crypto-native traders, US retail, political junkies, forecasters. Their collective opinion is the price, and different crowds genuinely disagree about probability.

Regulation & access

Kalshi is CFTC-regulated and US-legal; Polymarket is global and not open to US persons; PredictIt runs politics-only under a no-action posture. Walled-off user bases can’t arbitrage each other, so prices stay apart.

How to spot prediction market arbitrage

Because a Yes contract and a No contract together always settle at exactly $1, you can sometimes buy both sides across two platforms for less than $1 — locking in the difference whichever way the question resolves.

Say a market reads Yes 43¢ on Kalshi and No 55¢ on Polymarket. Back both and you’ve paid 98¢ to guarantee a $1 return — a 2¢ (≈2%) edge on every contract pair, no matter the outcome. The wider the cross-platform spread, the bigger the edge.

The catch: it is not free money. Trading and withdrawal fees, gas on crypto-funded venues, slippage in thin order books, and access rules (you can’t hold a US Kalshi position and a Polymarket one without clearing both KYC walls) can all eat a small edge. Treat a wide spread as a signal to investigate, size for the fees, and never assume the price you see is the price you’ll fill.

Strip the margin out of a two-sided market with the vig calculator →

For informational purposes only. Not betting or financial advice. Prices are illustrative demo data and may not reflect the live price at any platform — always confirm before trading. Please play responsibly. 18+ where applicable.