Polymarket US and Kalshi: Comparing the Total Cost of a Taker Purchase
The all-in cost of a prediction-market trade on Polymarket US and Kalshi depends on more than the quoted price of a contract. For eligible U.S. users trading directly on either platform, the applicable fees can also affect which venue offers the lower total purchase price. In some cases, the difference between the platforms’ fees may be smaller than the difference between their contract prices.
A hypothetical taker purchase illustrates how narrow that fee difference can be. Buying 100 contracts at 40 cents each produces a $40 contract value before fees. The total cost is $41.67 on Polymarket US and $41.68 on Kalshi, a difference of just one cent across the entire purchase.
The example implies fees of $1.67 on Polymarket US and $1.68 on Kalshi. On a per-contract basis, the all-in cost is 41.67 cents on Polymarket US and 41.68 cents on Kalshi. This is a hypothetical comparison rather than a live quote or a statement that every trade will carry the same totals.
Why Price and Fees Must Be Compared Together
The 40-cent starting price used for both platforms makes the fee comparison especially clear. Because the contract value is identical, the one-cent gap in the final totals comes from the difference in fees. Traders comparing Polymarket US directly with Kalshi should therefore consider the platform’s fee schedule alongside the price displayed for the contract they intend to buy.
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A small fee gap does not necessarily make the platforms’ economics identical on every trade. As the comparison notes, the fee difference can be smaller than the price difference. If the same contract is available at different prices on Polymarket US and Kalshi, that price gap may have a greater effect on the final cost than the fee difference shown in the example.
The calculation also demonstrates why the headline price of a 40-cent contract is not the same as the amount paid at checkout. The 100-contract position has a $40 base value, while the stated totals of $41.67 and $41.68 include an additional $1.67 or $1.68 in fees, depending on the platform.
Why This Matters for Eligible U.S. Traders
For eligible U.S. users trading directly on Polymarket US or Kalshi, choosing a platform based only on the quoted contract price can obscure the all-in expense. The relevant comparison includes both inputs: the price at which the contract is available and the fee charged under the applicable terms.
The example does not provide a broader survey of prices across the two platforms or indicate that one venue is always cheaper. It instead isolates the fee component in a defined scenario. Traders assessing a specific order can apply the same approach by calculating the contract value, adding the applicable platform fee and comparing the resulting totals.
Eligibility and direct trading status also remain important qualifiers. The figures are presented specifically for eligible U.S. users buying directly on Polymarket US and Kalshi, rather than for every user, contract or type of transaction.
Frequently Asked Questions
How much would 100 contracts at 40 cents cost on each platform?
The hypothetical taker purchase costs $41.67 on Polymarket US and $41.68 on Kalshi, including the stated fees.
What is the difference between the two example totals?
The total cost differs by one cent. The example implies fees of $1.67 on Polymarket US and $1.68 on Kalshi.
Does the one-cent difference mean every trade costs the same on both platforms?
No. The one-cent difference applies to the hypothetical purchase of 100 contracts at 40 cents. The broader point is that eligible U.S. users trading directly should compare both contract prices and fees, because the fee difference can be smaller than the price difference.
