Kalshi vs Polymarket vs Polymarket US: which can you use, and what does each cost?
ThinBlimp guide · facts checked October 28, 2026 against each venue's own fee pages and market data · nothing here is advice
Kalshi and Polymarket US are both exchanges regulated by the CFTC that trade in US dollars; Polymarket is a separate crypto exchange for traders outside the US. All three list many of the same markets, but on separate order books with their own fees, price steps and rules, so the same question can cost a different amount on each.
Who can use each one?
| Polymarket US | Polymarket | Kalshi | |
|---|---|---|---|
| Who can use it | US traders, after identity verification | Traders outside the US | US traders, and traders in many other countries, after identity verification |
| Regulated by | The CFTC | Not a US-regulated exchange | The CFTC |
| Money | US dollars | A dollar stablecoin | US dollars |
Availability in individual states has changed with court rulings this year. Check the venue before you sign up.
What does each one charge?
All three use the same shape of taker fee, rate × contracts × price × (1 − price), so the fee is largest at 50¢ and shrinks toward 0¢ and 100¢. The rate is what differs.
| Polymarket US | Polymarket | Kalshi | |
|---|---|---|---|
| Taker rate | 0.0695 (0.10 on table tennis) | 0.04 politics, 0.05 sports, 0.07 crypto | 0.07 on most markets |
| Fee on 100 contracts at 50¢ | $1.74 | $1.00 politics, $1.25 sports, $1.75 crypto | $1.75 |
| Rounding | To the nearest cent | To 5 decimal places | Up to the next cent, per order |
| Resting (maker) orders | No fee; a rebate at higher maker tiers | No fee | No fee on most markets |
Polymarket keeps each market on the rate it had when it listed, and each market's page states its rate. The fee calculator works out any trade on all three.
How small can a price move?
Each venue sets its own price step, and a smaller step lets the gap between buyers and sellers get tighter.
| Market, read October 28, 2026 | Polymarket US | Polymarket | Kalshi |
|---|---|---|---|
| Israel's next prime minister | 1¢ | 0.1¢ | 1¢ |
| An NFL game to win | 0.25¢ | varies by market | 1¢ |
On Polymarket US the step is set market by market: the same day a college football game moved in 0.5¢ steps and an NBA game in 1¢. Check the market itself before you price a small edge.
Is the price the same on all three?
Often close, never guaranteed. Before Seattle played at Denver on October 15, Seattle's best ask was 56.75¢ on Polymarket US and 57¢ on Kalshi. At 3:36 PM ET the books said a $10,000 buy would average 58.46¢ after fees on Polymarket US and 58.72¢ on Kalshi.
On a political market the gap can be much larger. At 10:45 PM ET on October 28, the day after Israel's election, Gadi Eizenkot's ask was 25.9¢ on Polymarket, 27¢ on Polymarket US and 14¢ on Kalshi, whose market settles on different rules. That example is worked through in why the same market has different prices.
Can I hold both Polymarkets?
Not as one account. Polymarket and Polymarket US are separate exchanges that share a name; a trade on one never touches the other. The full comparison is in Polymarket US vs Polymarket.
Questions
What is the difference between Kalshi, Polymarket and Polymarket US?
Kalshi and Polymarket US are CFTC-regulated exchanges that trade in US dollars. Polymarket is a separate crypto exchange for traders outside the US. They list many of the same markets on separate order books, with different fees, price steps and rules.
Which has the lowest fees, Kalshi or Polymarket US?
They are close. On 100 contracts at 50¢ the taker fee is $1.75 on Kalshi and $1.74 on Polymarket US. Polymarket charges $1.00 on politics and $1.25 on sports at the same price, but it is not open to US traders.
Can Americans use Polymarket?
Not Polymarket’s international exchange. Americans trade on Polymarket US, a separate CFTC-regulated exchange with US-dollar accounts and identity verification.
Why does Polymarket US quote prices like 56.75¢ when Kalshi uses whole cents?
Each venue sets its own price step. On October 28 Polymarket US’s NFL game lines moved in 0.25¢ steps and Kalshi’s in 1¢ steps.