Polymarket vs Kalshi Odds Explained
Two venues, the same question, two different prices. The gap is rarely a free lunch — it usually tells you something about collateral, fees, or who is allowed to trade.
Two exchanges, two very different structures
Kalshi is a CFTC-regulated designated contract market in the United States. Contracts are denominated in dollars, funded from a bank account, and the exchange operates under US derivatives rules. Polymarket settles on-chain, with positions collateralised in USDC, and grew up as a crypto-native venue with a global user base.
That structural difference drives nearly every price discrepancy you will observe between them. Before treating a gap as a mispricing, it is worth understanding which of these mechanics is producing it.
Why identical questions carry different prices
Collateral and opportunity cost. A dollar posted at Kalshi and a USDC posted at Polymarket are not economically identical. Stablecoin holders may have different yield alternatives, and crypto-native capital often carries a higher hurdle rate. That difference alone can shift a long-dated contract by a point or two.
Fee structure. Taker fees, maker rebates, and gas costs are not the same across venues, and they are charged at different points in the trade lifecycle. A price that looks two cents cheap can be exactly fair once the round trip is costed.
Access and participant mix. The two venues do not draw from the same pool of traders. Restrictions on who can trade what, and from where, mean the marginal price-setter on one venue may have a genuinely different information set than on the other.
Resolution wording. The most commonly missed factor. Two contracts can describe what sounds like the same event while resolving on different sources, different deadlines, or different definitions of what counts.
Liquidity depth matters more than the headline price
A quoted probability is only meaningful at the size you can actually transact. A market showing 62% with a hundred dollars of depth and a market showing 62% with fifty thousand dollars of depth are conveying very different amounts of information.
Depth also determines how much your own order moves the price. On a thin book, taking the other side of an apparent mispricing can move the market far enough that the edge disappears before your position is filled — which is why depth, not just the spread, is the practical constraint.
How to compare the two responsibly
Match the resolution criteria first, the price second. If the two contracts do not resolve on the same source with the same deadline, you are not comparing the same instrument and the spread is not a signal.
Then check depth on both sides, cost the full round trip including fees and any transfer costs, and ask whether the capital would be locked up until resolution. Many apparent spreads are simply the market pricing the cost of that lockup.
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See where the crowd stands now →Quick answers
Is Kalshi or Polymarket more accurate?
Neither is systematically more accurate. Accuracy tends to track liquidity and attention: whichever venue has deeper markets and more participants on a given question usually produces the better-calibrated price for that question.
Why do the same odds differ between Polymarket and Kalshi?
Differences in collateral and its opportunity cost, fee structures, who is permitted to trade, and — most often overlooked — subtle differences in how the contracts are worded and resolved.
Can I arbitrage the difference between the two venues?
Sometimes, but the apparent gap is frequently consumed by fees, capital lockup until resolution, and differences in resolution wording. Verify that both contracts genuinely resolve identically before treating a spread as free money.