Polymarket vs Kalshi: how the two biggest prediction markets differ
In short
What they have in common
Both are exchanges, not bookmakers: every share you buy is sold by another trader through an order book, and the venue earns fees or spreads instead of betting against you. A share costs between 1¢ and 99¢ and pays $1 if it is right, so a 62¢ price means the market sees about a 62% chance.
Both list elections, economic data and the Fed, crypto prices, sport and culture, and both publish written rules for each market with the source that decides it.
Regulation and where each is available
Kalshi is a designated contract market regulated by the US Commodity Futures Trading Commission (CFTC). It serves US customers, and some US states have challenged its sports contracts in court, so availability of those can depend on the state.
Polymarket's main exchange is international and settles in USDC, a dollar stablecoin. It has blocked US users since a January 2022 settlement with the CFTC. In 2025 it bought QCEX, a CFTC-licensed exchange, and it now serves US users through that separate app, Polymarket US, which was reported to open to all US iPhone users in May 2026. Several countries outside the US restrict or block the international exchange. Check each venue's own terms for where you live: this page is general information, not legal advice.
Money in and out
Kalshi works in US dollars: you fund it by bank transfer or card, and it also accepts some crypto deposits (such as USDC), which it converts to dollars. Polymarket's international exchange works in USDC on a blockchain network, funded from a crypto wallet or an exchange, and positions are held as on-chain tokens.
Fees
Kalshi charges a trading fee on most contracts, largest for prices near 50¢. Polymarket's international exchange charged no fee on most markets until 2026; as of October 2026 its fee docs list a taker fee on most categories, also largest near 50¢, with no fee on geopolitics and world-events markets and none for makers (orders that rest on the book). On both, the bid-ask spread is the other cost: on busy markets it is about 1¢.
How markets resolve
Kalshi decides outcomes itself under each contract's rules and named source. Polymarket markets are typically settled through UMA's optimistic oracle: a result is proposed after the event, can be disputed during a challenge window, and becomes final once undisputed or decided, which can take days on a contested market.
Which markets each is strongest in
Polymarket has the widest range of world events: elections in many countries, geopolitics, crypto and internet culture. Kalshi is strongest in US economic data, the Fed, US politics and US sport, and in 2026 it has traded more each month than Polymarket in the months reported (for example March and April 2026). Big events like a US election or a Fed decision trade on both, and the prices are usually close.
Where PredictRips fits
PredictRips is neither: it is a pack game built on Polymarket markets. A pack holds 3 random live positions at a fixed price, with the odds and pack value (about 90% of the price) shown before you pay. To pick one market and size your own trade, use an exchange.
Polymarket vs Kalshi at a glance (as of October 2026; check each venue's current terms)
| Polymarket | Kalshi | |
|---|---|---|
| Type | Crypto-native exchange (order book) | US exchange (order book) |
| Regulator | International exchange; separate CFTC-regulated app (Polymarket US) for US users | CFTC (designated contract market) |
| Currency | USDC stablecoin | US dollars |
| Fees | Taker fee on most categories since 2026 (none on geopolitics); no maker fee | Trading fee on most contracts |
| Resolution | Usually UMA optimistic oracle, under written rules | Kalshi, under each contract's rules |
| Strongest in | World politics, geopolitics, crypto, culture | US economics, the Fed, US politics, US sport |