Compared

Kalshi vs Polymarket: what's actually different

Kalshi and Polymarket list a lot of the same questions, from elections to the NFL. They differ in who can use them, how they settle money and what they charge. And because they're separate order books, the same event is often priced differently on each.

The short version

Fees from each venue's published schedule, checked October 31, 2026. All three use the same shape of formula: rate × contracts × price × (1 − price). Venues change fees, so check their own pages before trading.

Prices: why the same market costs different amounts

Kalshi and Polymarket don't share an order book. Each price comes from whoever is buying and selling on that venue. When news hits, one venue often moves first, and for a short time YES on one plus NO on the other can cost less than $1 in total. That's a cross-market spread.

Most gaps are small and close within minutes, and both venues charge a fee on each side. Near 50¢, fees on a two-sided trade between Kalshi and Polymarket US add up to about 3.5¢ per pair, so a gap has to be bigger than that to pay. Near 10¢ or 90¢, fees are about a third as large.

Settlement can differ too

Two venues can word the same question slightly differently, with different cut-off times or sources. A question that looks identical can settle differently on each. Before trading both sides, read both rules pages, not just the titles.

Which one should you use?

• In the US: Kalshi and Polymarket US are the regulated options. Taker fees are nearly the same; Polymarket US is a hair cheaper and doesn't charge makers.
• Outside the US: Polymarket's international site, which has the lowest fees on politics, finance and geopolitics markets.
• Both: many active traders keep accounts on more than one venue so they can take the better price on each trade.

Common questions

Is Kalshi or Polymarket cheaper?

For takers in the US they're nearly the same: Kalshi's rate is 0.07 and Polymarket US's is 0.0695, so 100 contracts at 50 cents cost $1.75 and $1.74. Polymarket US doesn't charge resting orders. Polymarket's international site is cheaper on politics, finance and geopolitics markets.

Can I use Polymarket in the US?

Polymarket US is the CFTC-regulated exchange for US traders. Polymarket's international site is for traders outside the US. Check each venue's own terms for where it's available.

Why are Kalshi and Polymarket prices different?

They are separate order books, so each price comes from that venue's own buyers and sellers. One often reacts to news first, which can leave a short-lived gap between them.

Can I make money from the price difference?

Sometimes, if the gap is bigger than the fees on both sides and both legs fill. Gaps are usually small, close fast, and the two venues can settle a question differently. It's an edge, not a sure thing.