Kalshi vs Polymarket

Kalshi vs Polymarket: the key differences

Kalshi and Polymarket US are both CFTC-regulated exchanges with their own clearinghouses, and both list yes/no contracts on sports, politics, crypto and economics. Kalshi ranks #1 and Polymarket US #4 in our ranking of the best US prediction markets, because Polymarket’s US exchange is newer and far smaller, takes fewer payment methods and pays no interest.

“Polymarket” here means Polymarket US, the exchange at polymarket.us and in its app. The international polymarket.com is close-only for US users: you can close existing positions but can’t open new ones.

As of September 30, 2026:

• Volume: Kalshi handled about $53 billion in September 2026 through the 29th, according to The Block. Polymarket US traded about $8.5 billion in the whole month, according to DeFi Rate data.
• Fees: takers pay at most 1.75¢ per contract on Kalshi and 1.74¢ on Polymarket US. Most Kalshi maker orders are free, while Polymarket US pays makers a rebate.
• Payments: Kalshi takes bank transfers, debit cards, Apple Pay, Google Pay, PayPal, Venmo, Cash App and crypto. Polymarket US takes debit card, ACH and wire only, and card and ACH withdrawals take 3–4 business days.
• Interest: Kalshi pays a 3.25% variable APY on cash and open positions for balances of $250 or more. Polymarket US pays none.
• State limits: court orders block Kalshi’s sports contracts in Nevada, Michigan and Washington. Polymarket US says it’s unavailable only in Nevada.

Fees

On fees alone, Polymarket US is slightly cheaper, but for takers the gap is tiny. Kalshi charges takers 0.07 × contracts × price × (1 − price), rounded up to the next cent (schedule effective July 7, 2026). Polymarket US charges 0.0695 × the same, rounded to the nearest cent (schedule effective September 25, 2026).

The real difference is for makers, whose limit orders wait on the book until someone trades against them. Most Kalshi maker orders pay nothing, while Polymarket US pays makers a rebate of 0.0125 × the same formula.

The Polymarket US figures at 20¢ and 90¢ are our calculations from its published formula. Buying 100 Yes contracts at 50¢ as a taker costs $51.75 on Kalshi and $51.74 on Polymarket US. As a maker, it costs $50.00 on most Kalshi markets, and $50.00 minus a $0.31 rebate on Polymarket US.

Other costs cut both ways:

• Polymarket US charges no deposit or withdrawal fees and gives traders with $250,000 or more of volume in the previous month 10% to 50% of their taker fees back, but its combos carry an extra taker charge.
• Kalshi’s bank deposits are free, but debit card deposits may cost 2%, and PayPal and Venmo deposits after the first carry a fee.
• Kalshi pays interest: at a 3.25% variable APY, a $1,000 balance earns about $32.50 a year if the rate stays the same.

Our prediction market fees guide compares all five platforms we rank.

Liquidity

Kalshi is far more liquid, and more volume generally means tighter prices and more room to trade larger sizes without moving the market. Combos alone made up about 62% of Kalshi’s volume in the week of September 14–20, 2026, according to DeFi Rate data. Polymarket US is much younger: it opened to invited users in December 2025 and dropped its iOS waitlist on May 12, 2026.

One caveat: in September 2026, traders and Wall Street Journal reporting alleged inflated volume in Kalshi’s ETH perpetual futures, a separate product from its event contracts. Kalshi denies wash trading and has filed to end its Volume Incentive Program no earlier than October 13, 2026.

Availability and legality

Both are legal under federal law, but as of September 30, 2026, each is blocked or sued in different states.

Polymarket US’s App Store listing names only Nevada, but some third-party guides list up to eight more excluded states, so check the app before you deposit. Federal appeals courts are split on sports contracts: the Third Circuit sided with Kalshi, while the Ninth and Sixth Circuits sided with the states. None of the three related Supreme Court petitions had been granted as of September 30.

Kalshi has the longer regulatory record: its exchange has been CFTC-designated since November 2020, and the CFTC used emergency powers twice on its behalf in 2026. Polymarket US’s exchange, QCX LLC, was designated in July 2025, and in January 2022 the CFTC ordered Blockratize, the company behind Polymarket, to pay $1.4 million and wind down markets it had offered without registering. Our guide to whether prediction markets are legal tracks the cases.

Federal registration doesn’t override a court order in your state. Trade only what each app offers where you are, and don’t use a VPN to get around a block.

Outside the US, neither Kalshi nor Polymarket is licensed in Spain or Brazil; see our guides for Spain and Brazil.

Which should you choose?

Choose Kalshi if you want the deepest order books and the widest choice of markets, want to fund with PayPal, Venmo or crypto, or keep money on the platform and want interest on it.

Choose Polymarket US if you mostly post limit orders and want a rebate rather than a zero fee, trade enough volume to get part of your taker fees back, or are in Washington and want politics markets, which a court order blocks on Kalshi there.

Using both can make sense: two accounts let you compare prices on sports and politics markets, though each needs its own ID check and deposit. Whichever you choose, set a budget first. Kalshi offers a trading break, self-exclusion and a monthly funding cap; Polymarket US’s tools couldn’t be confirmed, so see our responsible gambling guide.

Read our full Kalshi review and Polymarket review, or see how both compare with Robinhood, OG and Interactive Brokers in our complete ranking of US prediction markets.