Polymarket vs Kalshi

Fee Structure: What You Actually Pay

Polymarket charges 0% on trades. That number needs context: the platform earns revenue through market spreads, which means liquidity providers capture the margin between bid and ask prices. For traders, this translates to a small implicit cost per trade rather than a stated fee. On high-liquidity markets like major elections, these spreads are tight — effectively making the cost close to zero. On thinner markets, spreads widen and the implicit cost rises.

Kalshi charges approximately 7% on net winnings, not on each trade. If you trade $100 and win $20, the fee is roughly $1.40. If you lose, you pay nothing. This structure is more predictable than spread-based pricing and may actually favor casual traders who make occasional, well-considered trades rather than high-frequency participants who accumulate spread costs.

For practical comparison: a $500 winning position on a 50/50 market would cost roughly $35 in Kalshi fees (7% of $500 net win). The equivalent trade on Polymarket in a liquid market might cost $5-15 in spread. The gap narrows significantly in lower-liquidity Kalshi markets where spreads also exist.

Market Selection and Liquidity

Polymarket has the deeper market selection by a significant margin. As of 2026, the platform routinely runs thousands of simultaneous markets spanning US and international politics, cryptocurrency prices, sports outcomes, technology milestones, and global events. The 2024 US election cycle alone saw hundreds of millions in trading volume on a single market — a level of liquidity that produces tight, accurate prices.

Kalshi's selection is smaller and more curated, focused on US-relevant event contracts: elections, Federal Reserve decisions, economic indicators, weather events, and some sports markets. The platform is growing rapidly and has added categories including climate and science markets, but the breadth is not comparable to Polymarket for international events. What Kalshi offers that Polymarket cannot: CFTC-regulated contract settlement with legal certainty around resolution disputes.

For most traders, the relevant question is not total market count but whether the specific events you want to trade on are available. US political traders will find adequate coverage on both platforms for major races. International event traders will find Polymarket significantly better.

Onboarding and Trading Experience

Kalshi requires a US bank account, identity verification (standard KYC), and a $5 minimum deposit. Sign-up takes about 10 minutes. The web interface and mobile app are straightforward — you browse markets, click YES or NO, enter a dollar amount, and execute. No crypto knowledge required.

Polymarket requires a crypto wallet (typically MetaMask), USDC purchased from an exchange like Coinbase, and a wallet connection to the platform. The initial setup takes 20-40 minutes if you're new to crypto. Once set up, trading is fast. There is no mobile app — the platform is web-only. US residents cannot sign up regardless of technical ability.

The practical implication: Kalshi is accessible to anyone in the US with a bank account. Polymarket is accessible to anyone outside the US who is comfortable with basic crypto mechanics. These are genuinely different audiences, and for most beginners outside the crypto world, Kalshi's onboarding is significantly smoother.