Kalshi vs Polymarket: Which Prediction Market Should You Use?

Updated April 2026

Kalshi and Polymarket are the two largest prediction markets, but they work very differently. Kalshi is a CFTC-regulated US exchange trading event contracts in USD. Polymarket is a crypto-native platform using USDC on the Polygon blockchain. This guide breaks down everything you need to know to choose between them — or use both.

Side-by-side comparison

Regulation and access

The biggest difference is regulatory. Kalshi is the first CFTC-regulated prediction market exchange in the US, meaning it operates under strict financial oversight. You need to verify your identity (KYC) and can deposit via bank transfer or debit card. This makes it the straightforward choice for US-based traders who want legal certainty.

Polymarket operates offshore and uses crypto wallets for deposits and withdrawals. There’s no KYC requirement — you connect a wallet and trade. This makes it more accessible globally but puts it in a regulatory gray area for US users. Most serious US traders use Kalshi for compliance reasons, while international traders often prefer Polymarket for its larger market selection and higher liquidity.

Market selection

Both platforms cover politics, economics, and crypto, but the mix is different. Kalshi has deep coverage of US economic data (Fed rates, CPI, GDP, jobs reports) and granular sports markets (player props, game outcomes). Polymarket leans into crypto events, global politics, AI developments, and cultural events.

Many major events are listed on both platforms — elections, Fed decisions, major economic indicators. When the same event trades on both, you can compare prices and find arbitrage opportunities when prices diverge.

Fees and costs

Kalshi’s fees are built into the spread and vary by market. There’s no separate commission — the cost is in the bid-ask spread, which tends to be tighter on high-volume markets and wider on less liquid ones. Deposits and withdrawals in USD are free.

Polymarket charges approximately 2% on net winnings (profits minus losses). There are no fees on losing trades. However, you’ll also pay blockchain gas fees for deposits, withdrawals, and sometimes order placement. These are usually small (cents) on Polygon but can add up for frequent traders.

Liquidity and volume

Polymarket generally has higher liquidity on its top markets, especially political and crypto events. Some major Polymarket markets see millions in daily volume. Kalshi’s liquidity is growing but tends to be lower per-market, with volume concentrated in economics and elections.

For traders, liquidity matters because it affects how easily you can enter and exit positions at your desired price. On low-liquidity markets, large orders can move the price against you (slippage). This is why tracking whale trades is valuable — large trades on thin markets can create temporary mispricings.

APIs and automation

Both platforms offer APIs for programmatic trading. Kalshi has a REST API with public endpoints for market data and authenticated endpoints for order placement. Polymarket offers a CLOB (Central Limit Order Book) API for trading and a Gamma API for market discovery.

If you’re building bots or automated strategies, having API access to both platforms is essential. CrossOdds provides a unified API that aggregates data from both Kalshi and Polymarket, so you can query arbitrage opportunities and whale trades from a single endpoint.

Which should you use?