Kalshi vs Polymarket
Polymarket is the largest crypto-native prediction market — peer-to-peer trading on USDC, hosted on Polygon, regulated outside the U.S. Kalshi and Polymarket are the two most-traded event-contract exchanges in the world, but they differ on legal access, fee structure, and market depth. This page compares the two head-to-head.
FAQ: Kalshi vs Polymarket
Can U.S. residents use Polymarket?
Officially no. Polymarket settled with the CFTC in January 2022 and geo-blocks U.S. IP addresses. Some U.S. residents reportedly use VPNs to access the platform, but this violates Polymarket's terms of service. For legal U.S. event-contract trading, use Kalshi.
Which has cheaper fees: Kalshi or Polymarket?
Depends on bet size. Polymarket charges 0% trading fees but you pay gas to settle on-chain (typically $0.01-$0.50 per trade on Polygon). Kalshi charges max 7¢ per contract (peaks at 2¢ near 50% probability). For positions over ~30 contracts, Kalshi tends to be cheaper. For small positions, Polymarket's no-fee model wins.
Do Kalshi and Polymarket prices differ on the same event?
Yes, often by 1-5 percentage points on liquid markets, sometimes more on illiquid ones. The gap reflects: different user bases (Polymarket is more crypto-native + international; Kalshi is U.S. retail), different fee structures affecting marginal traders, and arbitrage friction (you can't easily move money between the two). SportsBookISH surfaces these gaps when both venues list the same market.
Is Polymarket safer than Kalshi?
From a U.S. regulatory perspective: no. Kalshi is CFTC-registered as a Designated Contract Market with full federal oversight, FDIC-equivalent customer fund segregation, and U.S. legal recourse for disputes. Polymarket operates outside U.S. jurisdiction — your funds sit in a self-custodial wallet (smart contract risk) and there's no consumer-protection framework if something goes wrong. From a smart-contract / decentralization perspective, Polymarket's contracts have been audited and operate transparently on-chain, which some users prefer.
Can I arbitrage Kalshi vs Polymarket?
Theoretically yes when the two venues price the same event meaningfully apart. Practically: capital lock-up across two platforms, FX/USDC conversion costs, gas fees on Polymarket, and counterparty risk on both sides eat most of the edge. SportsBookISH tracks the Kalshi vs Polymarket spread on overlapping markets so you can see when the gap is wide enough to be worth the friction.
Which platform has better political markets?
Polymarket — both by volume and breadth. Polymarket has historically led on election markets (presidential, primary, congressional) with hundreds of millions of dollars in volume per major election cycle. Kalshi has competitive election markets within its CFTC-approved categories but a smaller set of long-tail political contracts. For sports, the comparison flips: Kalshi has wider U.S. sports coverage.
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