Polymarket vs Kalshi: Which Prediction Market Should You Use?

The 30-second summary

• Polymarket: on-chain, USDC settlement, global access (outside restricted countries), larger selection of markets, deeper liquidity on political and crypto events
• Kalshi: CFTC-regulated, USD settlement, US-only, narrower market selection but heavy sports coverage since the 2025 ruling, friendlier UX for non-crypto users
• Use Polymarket if: you're comfortable with crypto wallets, you trade a variety of markets, you're not US-based or you want access outside Kalshi's offerings
• Use Kalshi if: you want traditional brokerage UX, you're US-based and want clear tax reporting, or you primarily trade sports

Fees

Polymarket charges no trading fees directly — you pay the bid-ask spread and gas for wallet operations. For active traders this is effectively zero on the trade itself, though Polygon gas adds up over many small orders.

Kalshi charges a small maker/taker fee that varies by market — typically 1-3% of the premium, capped. On low-premium trades (e.g. a 95¢ contract) the fee as a percentage of potential profit can be significant.

Winner: Polymarket for volume traders, Kalshi for occasional traders who don't want to manage a wallet.

Liquidity and market depth

Polymarket has dominant liquidity on politics, geopolitics, and crypto markets. Top events like US elections routinely cross $100M in traded volume. Tail markets are thinner — you'll see wide spreads on obscure events.

Kalshi has built strong liquidity on sports markets since the CFTC approved event contracts on sports in 2025. For politics, Kalshi is catching up but still lags Polymarket by an order of magnitude in volume.

Market selection

Polymarket lists thousands of markets across politics, crypto, sports, pop culture, science, and recurring events. The listing process is curated but relatively fast — a newsworthy event typically gets a market within hours.

Kalshi lists fewer markets but each one is standardized under a CFTC-approved rulebook. Fewer edge cases in resolution, but also fewer niche markets. If you want to trade "will Taylor Swift announce a tour in 2026?", Polymarket has it and Kalshi probably doesn't.

Resolution and disputes

Polymarket uses UMA's optimistic oracle for resolution, with a bond and dispute window. Most markets resolve cleanly, but controversial edge cases (ambiguous wording, unexpected events) can go to dispute and take longer. A small percentage of markets have had contested resolutions.

Kalshi resolves internally based on pre-specified data sources. More predictable, fewer disputes, but less flexibility when the real world doesn't fit the rulebook.

Tax and reporting

Kalshi issues 1099s. US traders get clean tax reporting without extra tools.

Polymarket doesn't issue tax forms. You're responsible for tracking your own P&L and reporting it — typically as capital gains or, in some jurisdictions, gambling income. Tools like CoinTracker can help, but it's extra work.

Copy trading and automation

Polymarket has a public on-chain order history, which makes copy trading straightforward — any wallet can be followed. Platforms like Polybuild mirror top trader positions automatically.

Kalshi's trade data is not on-chain, and their API doesn't expose other users' activity. Copy trading in the Polymarket sense isn't possible on Kalshi today.

Which should you pick?

If you're new to prediction markets and based in the US, start with Kalshi — the UX is familiar and you won't get tangled in wallet setup. If you're comfortable with crypto or outside the US, Polymarket gives you more markets, better liquidity on the big events, and access to copy trading infrastructure.

Many serious traders use both: Kalshi for sports and clean tax reporting, Polymarket for everything else.