Kalshi processed about $13.8 billion of the total $16.3 billion traded across both platforms in the 30 days to September 24th, 2026, reflecting an 85% share. “Polymarket” operates two platforms: Polymarket US, run by QCX LLC, and an international website for its international customers.
Kalshi vs Polymarket Verdict
Pick Kalshi If
You want depth and broader market options. Kalshi publishes contracts across financial indices, economics, weather, ports, science, culture, and crypto, and the site’s 30-day volume dwarfs the competition. Kalshi also lists and clears its own contracts. KalshiEX LLC is the designated contract market, while Kalshi Klear LLC handles clearing.
Pick Polymarket If
You trade crypto, politics, and geopolitics, and want a central limit order book paired with a maker rebate. Polymarket US credits rebates to resting orders, which Kalshi doesn’t offer on most markets.
Polymarket’s volume is just a fraction of Kalshi’s, and it boasts an international platform that US traders can’t use.
Where They Are Identical
The CFTC designates both platforms as contract markets, and lists binary contracts that are priced in cents and settled at $1 or zero. Both are fully collateralized, with no leverage or margin.
Don’t expect casino-style welcome offers with a wagering requirement. For a clearer understanding of the market, check our prediction markets hub.
Access and Incentives Compared
What Each One Offers a New Trader
Neither platform boasts a deposit match bonus with a playthrough requirement, so their differences lie elsewhere. For Kalshi, new customers can earn trading credits after making a qualifying trade. These credits can’t be withdrawn as cash, and expire if unused. The terms for free credits often change without notice, so check your account for the latest information.
Get the latest Kalshi offers for new players.
Where Kalshi Faces State Orders
Kalshi is under court orders in Nevada, Washington, and Michigan, and its availability to local traders has changed with litigation. In Michigan, an Ingham County court issued a temporary restraining order on June 29, 2026. Then on July 14th, the CFTC told Kalshi not to cancel Michigan traders’ open trades.
US Access to Polymarket
US traders can only access Polymarket US since the international platform blocks US IP addresses. Its US-facing platform was relaunched in December 2025 and dropped the waitlist in May 2026. Trades in Polymarket US are completed in US dollars.
Discover other venues in our prediction markets hub.
Fees, Settlement and Price Gaps
What Each Trade Costs
Kalshi and Polymarket charge a price-weighted taker fee, so neither is a fixed fee. Kalshi’s fee follows this computation: 0.07 × contracts × price × (1 − price). Polymarket US uses the same formula, but with a coefficient of 0.0695 as of September 17th, 2026, up from 0.06 and 0.05 earlier in the year.
| Price | Kalshi taker, per 100 contracts | Polymarket US taker, per 100 contracts | Polymarket US maker rebate |
| 10c | $0.63 | about $0.63 | about $0.11 |
| 50c | $1.75 | about $1.74 | about $0.31 |
| 90c | $0.63 | about $0.63 | about $0.11 |
As a share of the amount the trader puts in, that’s 6.3% at 10c, 3.5% at 50c, and 0.7% at 90c. Kalshi’s makers don’t get paid on most markets, while Polymarket US does. To get a clearer understanding of how fees work, check this prediction market fees guide.
How Each Contract Settles
Settlement is the defining factor in comparing operators in this vertical. Kalshi identifies the source fo each contract in its rulebook before publishing it, backing it up with official government data and statistics, official league results for sports, and NOAA data for weather contracts. All contracts are filed with the CFTC under Regulation 40.2, a day before publication.
Polymarket’s international contracts are resolved by the UMA optimistic oracle, where the proposer posts a bond, and challengers can escalate to a token-holder vote. Polymarket US is the designated contract market and publishes the contracts under its rulebook, so always verify the contract rules for the recommended source. For example, an economics contract should be based on an official government report.
Why the Two Books Show Different Prices
The two books work differently, with separate participants, fee stricture, and contract rules. A price gap is worth checking if it beats the fee at the listed price.
At 50¢, the taker fee is 1.75¢ per contract, so a pair of trades will cost you 3.5¢ before the gap pays anything. Contracts that may appear similar may still resolve under different rules.
