Polymarket vs Kalshi

Polymarket and Kalshi are the two largest prediction markets. They look similar — both let you trade on real-world events — but they're built on fundamentally different foundations. That difference shapes everything: who can use them, what they cost, how deep the liquidity runs, and what kind of trader each one suits.

The fundamental difference

Polymarket is built on Polygon, an Ethereum layer-2 blockchain. You trade with USDC (a dollar-pegged stablecoin), connect a crypto wallet, and interact with smart contracts. It operates without a specific regulatory license and is accessible globally — except to US residents, who are restricted by the platform's terms of service.

Kalshi is a CFTC-regulated exchange — a designated contract market (DCM) under US law. You trade with US dollars, connect a bank account, and your funds are held in segregated accounts with regulatory oversight. It's available only to US residents and operates under the same regulatory framework as futures exchanges.

This isn't a minor detail. It defines the trade-off: Polymarket gives you more freedom and more markets; Kalshi gives you more protection and less counterparty risk.

Markets and selection

Polymarket lists thousands of markets across politics, crypto, sports, entertainment, science, and current events. New markets can be created quickly, and the platform tends to list anything that generates trading interest. This breadth is a genuine advantage — if something is happening in the world, there's probably a Polymarket market for it.

Kalshi's market selection is more curated. Every contract must be approved under CFTC rules, which means the listing process is slower and more conservative. Kalshi focuses on economics, weather, politics, and financial events — areas where regulatory approval is more straightforward. The result is fewer markets, but each one has gone through a compliance review.

Fees and costs

Both platforms use a maker-taker model:

• Polymarket: 0% maker fee, 1–2% taker fee. Gas on Polygon is fractions of a cent. Depositing requires bridging USDC (which has its own gas cost on Ethereum L1).
• Kalshi: 0% maker fee, per-contract taker fee that varies by volume tier. No gas costs. Deposits and withdrawals via ACH bank transfer (free) or wire.

The explicit fees are comparable, but the real cost of trading is dominated by the spread and slippage — not the fee schedule. On high-volume markets, Polymarket typically has tighter spreads due to deeper order books. On smaller markets, both platforms can have wide spreads that make the taker fee look trivial by comparison.

See Polymarket Fees Explained for a deeper breakdown of what trades actually cost beyond the fee schedule.

Liquidity and volume

Polymarket has significantly higher volume on major markets, particularly political events. During the 2024 US election cycle, Polymarket processed billions of dollars in trading volume — far exceeding Kalshi's numbers for the same events. This volume translates to tighter spreads, deeper order books, and less slippage on big markets.

Kalshi's liquidity has grown substantially, especially after expanding into political markets. For US-focused events (elections, economic data releases, weather), Kalshi can be competitive on liquidity. But on global events, crypto markets, and niche topics, Polymarket's order books are typically deeper.

For any trader, liquidity matters more than fees. A market with zero fees but a 5-cent spread costs you more than a market with a 2% fee and a half-cent spread.

User experience

Polymarket has a clean, modern interface that's accessible to non-crypto users — but the onboarding still involves setting up a wallet and understanding USDC. The trading interface shows basic price charts and an order form. What it doesn't show: detailed order book visualization, per-position P&L tracking, or cost-basis reporting.

Kalshi has a more traditional exchange interface. Onboarding is familiar to anyone who's opened a brokerage account — KYC verification, bank linking, and you're trading in dollars. The interface is straightforward but similarly limited in advanced analytics.

Neither platform is designed for the kind of trader who wants real-time risk monitoring, automated exits, or honest P&L tracking. Both give you a betting slip; serious traders build tooling on top — or use a trading terminal that adds the missing layers.

Regulation and risk

This is where the platforms diverge most sharply:

• Kalshi's advantage: CFTC regulation means segregated customer funds, audited operations, and a regulatory body you can complain to. If Kalshi goes down, your funds have legal protections that crypto platforms don't offer.
• Polymarket's risk: Your funds are in a smart contract on Polygon. The platform is not regulated by any specific financial authority. If there's a dispute about market resolution or a platform issue, there's no regulator to appeal to. You're trusting the platform and the smart contracts.

For small amounts, this difference might not matter. For larger portfolios, the regulatory protection of a DCM is a meaningful advantage. The flip side: regulation also limits what Kalshi can list and how fast it can move.

API and automation

Both platforms offer APIs for programmatic trading:

• Polymarket uses a CLOB (Central Limit Order Book) API with WebSocket feeds. Authentication involves Ethereum key signing. The API is well-documented and actively used by automated traders. See the Polymarket API guide for details.
• Kalshi offers a REST API with WebSocket streams. Authentication uses API keys. The API is more straightforward (no crypto signing) but has stricter rate limits on some endpoints.

For developers building trading tools, Polymarket's API is more flexible but requires crypto infrastructure (wallet management, transaction signing). Kalshi's API is simpler to get started with but more limited in what you can do programmatically.

Which one should you use?

The honest answer: it depends on three things.

1. Where you live. If you're a US resident, Kalshi is your regulated option. Polymarket's terms restrict US trading.
2. What you trade. If you want the widest market selection and deepest liquidity on major events, Polymarket has more. If you focus on US economics, weather, and regulated political markets, Kalshi covers you.
3. How much you trade. For larger positions, Kalshi's regulatory protections and fund segregation matter. For smaller, exploratory trading, the difference is less material.

Many serious prediction-market traders use both — Kalshi for regulated markets where they want fund protection, and Polymarket for the broader selection and deeper liquidity on major events. The platforms aren't direct substitutes; they serve different needs.

Frequently asked questions

Is Polymarket or Kalshi better?

It depends on what you're looking for. Polymarket has more markets, higher volume, and is accessible globally — but it's crypto-native and unregulated. Kalshi is CFTC-regulated and uses US dollars, but has fewer markets and is restricted to US residents. Serious traders who want the deepest liquidity tend toward Polymarket; those who want regulatory protection lean toward Kalshi.

Can US residents use Polymarket?

Polymarket's terms restrict US residents from trading on the platform. However, the browse-only experience is available to everyone. Kalshi is the CFTC-regulated alternative specifically designed for US residents.

What are the fees on Polymarket vs Kalshi?

Both platforms use maker-taker fee models. Polymarket charges 0% for makers and 1–2% for takers. Kalshi charges 0% for makers and a per-contract fee for takers that varies by volume tier. Both have minimal or no withdrawal fees, but Polymarket requires crypto bridging while Kalshi uses standard bank transfers.

Which prediction market has more liquidity?

Polymarket generally has deeper liquidity on major markets, especially political and crypto-related events. Kalshi's liquidity has grown significantly but tends to be concentrated in US-focused events. For the biggest markets (elections, major geopolitical events), Polymarket typically has tighter spreads and more depth.