Prediction market fees compared: Hyperliquid, Polymarket and Kalshi

On an exchange, a fee is a percentage of your trade. On prediction markets, the two big platforms that charge use a different formula, one that depends on the price. It is small, it is fair in its own way, and it is easy to underestimate. This guide puts every rule side by side, with dates and sources, and works through real numbers.

How much do prediction markets charge?

Hyperliquid outcome markets charge nothing to open and about 0.07% when you sell or settle. Polymarket charges takers on some categories. Kalshi charges takers and makers by a published formula. Here is the summary for 100 shares at $0.50, a $50 trade.

C is the number of shares or contracts and p or P is the price. Sources: >Hyperliquid docs, HIP-4, >Polymarket docs, fees, >Kalshi fee schedule.

What does Hyperliquid charge on outcome markets?

Nothing to open a position. In our check of fills on October 18, 2026, Hyperliquid took about 0.07% when a position was sold or settled. Its HIP-4 docs still say fees are "currently zero for outcome markets for initial testing", so trust the fee shown on the trade screen.

BlockEden summed up the launch design as "Zero fees to open. Fees only when you close, burn, or settle" (>BlockEden). A developer guide adds that fee rates come from the same per-user tier as Hyperliquid's other markets, and that outcome trading pays no maker rebates (>Chainstack developer guide). A current guide confirms that opening a position carries no Hyperliquid fee (>QuickNode guide).

What do apps add on top of Hyperliquid?

Apps can charge a builder fee through builder codes. For outcome markets, builder codes work as they do in spot trading, where the cap is 1%. The app must show it to you.

The HIP-4 docs say builder codes apply to outcome markets as in normal spot trading, with builders earning fees on sell orders that include their code (>Hyperliquid docs, HIP-4). The builder codes page sets the caps: "Builder fees charged can be at most 0.1% on perps and 1% on spot" (>Hyperliquid docs, builder codes). You approve a builder's maximum fee once, with a signature, before it can charge you. Builder fees on perps are explained in Hyperliquid fees explained.

How does Polymarket charge?

Polymarket charges a taker fee on some categories, by the formula C x feeRate x p x (1 - p). Makers are never charged. Geopolitics and world events markets are free.

Polymarket's docs add that fees are paid in USDC, rounded to 5 decimal places, and that it charges nothing to deposit or withdraw USDC, although services like card on-ramps may charge their own fees (>Polymarket docs, fees). Rates were read on October 18, 2026, and the page shows no date, so check it before you trade.

How does Kalshi charge?

Kalshi's general taker fee is 0.07 x C x P x (1 - P), and its maker fee uses 0.0175 instead of 0.07, both rounded up. The schedule is dated and effective July 7, 2026.

The fee schedule rounds so that the fee plus the position cost lands on a centicent, a hundredth of a cent (>Kalshi fee schedule). Like Polymarket's, Kalshi's formula is largest at a 50% price. Kalshi is a US exchange regulated by the CFTC as a Designated Contract Market (>Kalshi help center).

Why do these fees peak at 50%?

Because p x (1 - p) is largest when p is 0.50. In dollars the fee peaks there, but as a share of what you pay, cheap sides pay the most.

Polymarket's docs note that a 30-cent and a 70-cent trade carry the same dollar fee, which is the same symmetry (>Polymarket docs, fees). For a long shot at $0.10, a 4.5% fee is a big bite out of a bet that already wins only about 1 time in 10.

What other costs are there?

The spread, swaps into the right stablecoin, and moving money in and out. They can cost more than the fee.

• Spread. The best buy price sits above the fair price. Buying at $0.52 on a fair $0.50 costs 2 cents a share, more than any fee above.
• No stablecoin swap anymore. HIP-4 markets used USDH at launch and now use USDC, so USDC on Hyperliquid is enough.
• Withdrawals. On Hyperliquid, a USDC withdrawal costs $1, taken by Hyperliquid to pay the network.
• Selling early. Every exit before settlement is a new trade, with its own spread.

How do the fees compare on a $10 trade?

On $10 at $0.50, so 20 shares, fees range from $0 to $0.35. The spread will often matter more than that.

We use $10 here because it is Hyperliquid's minimum per order on outcome markets (>QuickNode guide).

What does CopyHype charge on predictions?

1% when you buy, 1% when you sell before the result, and nothing from CopyHype at the result. From $10 a bet. On $10 at $0.50, you pay $10.10; selling early at $0.70 costs $0.14 to CopyHype. Hyperliquid's own fee, about 0.07%, comes on top when you sell or settle. Practice money carries the same trading fees so the results match.

Predictions are live in CopyHype, with free practice money first. How it works: Predictions in CopyHype.

Frequently asked questions

Are Hyperliquid prediction markets free?

Not quite. Opening a position is free, and in our check on October 18, 2026, Hyperliquid took about 0.07% when selling or at settlement. Apps can add a builder fee, and fees can change.

How is the Polymarket fee calculated?

C x feeRate x p x (1 - p), where C is the number of shares and p the price, on some categories only. Makers pay nothing.

What is Kalshi's fee on a 50 cent contract?

With the general taker formula, 0.07 x 0.50 x 0.50 = 1.75 cents per contract, rounded up. That is $1.75 on 100 contracts.

Why does a cheap side pay a bigger fee in percent?

Because the fee depends on p x (1 - p), which falls slower than the price. At $0.10, a Polymarket sports fee is 4.5% of the price; at $0.50 it is 2.5%.

Does CopyHype charge a fee on predictions?

Yes: 1% when you buy and 1% if you sell before the result, with nothing from CopyHype at the result.

Where do these facts come from?

From each platform's fee docs, Hyperliquid's builder codes page, and launch reports, checked on October 18, 2026. Sources:

• >Hyperliquid docs: HIP-4 outcome markets
• >Hyperliquid docs: builder codes
• >Polymarket docs: fees
• >Kalshi fee schedule
• >Kalshi help center: how is Kalshi regulated
• >Chainstack developer guide: HIP-4 outcome markets trading
• >QuickNode guide: trade HIP-4 prediction markets
• >Dwellir: HIP-4 on mainnet
• >BlockEden: HIP-4 goes live, May 8, 2026

Fee rules change. Kalshi's maker figure is rounded, and some Kalshi markets may use their own fee terms.