What are Polymarket's trading fees?
Polymarket's fee model runs on a formula: Fee = Theta x C x p x (1 - p). Theta is the fee rate for the market category. C is the number of contracts. p is the price per contract.
The mechanic that matters: the fee peaks when a contract is priced at 50 cents. That is where p x (1 - p) is highest, at 0.25. At price extremes, the fee falls toward zero. A contract priced at 10 cents costs roughly 36% as much in fees as the same contract at 50 cents.
Makers pay no taker fees. Polymarket runs a maker rebate program: post a limit order that others fill and you earn back a portion of the fees collected. That is the same incentive structure as institutional markets. Provide depth, pay less.
The formula also explains why spreads matter. A market with wide spread and high share volume generates meaningful fee drag on round trips. Active traders who treat Polymarket seriously track their effective fee rate alongside their hit rate. Execution quality starts with knowing the cost.
Polymarket fee schedule by category (July 2026)
The fee rate theta differs by category. Sports fees rose in July 2026. Here is the current schedule, sourced from Polymarket's official fee documentation.
Example: 100-share taker order on a crypto market at $0.50 per contract. Fee = 0.07 x 100 x 0.50 x 0.50 = $1.75. Same trade on a geopolitical market: Fee = 0 x 100 x 0.50 x 0.50 = $0.00. Same position size. One costs $1.75. The other costs nothing.
Polymarket US runs a uniform theta of 0.06 across all categories, with a maximum taker fee of $1.50 per 100 shares at 50 cents and a maker rebate of 25% of the matched taker fee.
- Geopolitical and economic markets: Theta 0, $0 taker fee. Free to trade.
- Tech and Mentions markets: Theta 0.04, $1.00 per 100 shares max at 50 cents.
- Sports markets: Theta 0.05, $1.25 per 100 shares max at 50 cents. Updated July 2026 from Theta 0.03 ($0.75 max).
- Crypto markets: Theta 0.07, $1.75 per 100 shares max at 50 cents.
How do Polymarket fees compare to Kalshi?
Kalshi's peak taker fee is also $1.75 per 100 shares at 50 cents. The same formula, a 7% taker rate, applied at 50 cents: 7% x 0.25 x 100 = $1.75. On crypto and high-fee categories, the venues are equivalent in fee structure.
The divergence is on political and economic markets. Polymarket's theta for those is zero. Free. Kalshi applies its 7% taker rate across all categories, which means a political contract at 50 cents carries the same $1.75 maximum as a crypto contract.
On a 100-share position in a political market priced at 50 cents, that is the difference between $0 on Polymarket and $1.75 on Kalshi. For traders running consistent volume in political markets, venue choice is a real cost structure decision, not a preference.
Full breakdown of Kalshi's pricing and structure: Kalshi review. For the complete side-by-side on liquidity, fees, and access: Kalshi vs. Polymarket.
Are there fees on Polymarket winnings?
No. Polymarket charges zero fees on winnings. The fee is collected at trade execution, not at resolution. What you win, you keep.
Traditional sportsbooks charge a vig of 5% to 10% on winning positions. That vig means you need to be correct well above 50% of the time just to break even on a near-coin-flip market. Polymarket's structure removes that drag. The cost is front-loaded into the taker fee at the point of the trade.
This matters for how you calculate expected value. A taker fee at execution is visible, countable, and consistent. You know it before you trade. That is cleaner math than a back-end vig on your winnings.
High-probability contracts get some relief from the formula. A contract priced at 90 cents carries a fee of Theta x 100 x 0.90 x 0.10 = Theta x 9, versus Theta x 25 at 50 cents. Near certainties cost far less in fees than near coin flips.
How Kairos works with Polymarket and Kalshi
Kairos puts Kalshi, Polymarket, and Predict.fun in one order book. Sub-second data, aggregated across all three venues in real time. When a market is listed on both Kalshi and Polymarket, Kairos shows prices from both.
That visibility, combined with knowing the fee structure, is where the edge lives. On a political contract near 50 cents, Polymarket's taker fee is $0. Kalshi's is up to $1.75. The better venue for that trade is not visible inside either platform's native interface. You see it inside a terminal.
Kairos is built for traders who want institutional-grade execution on prediction markets. Real-time data across all three venues. Advanced order types including limit orders and trailing stops. Aggregated liquidity at the global best bid and best ask. The power of an institutional trading desk, on your laptop. Event contracts carry real market risk. Fees are one cost. Being wrong is the other.
For automated execution on Polymarket, see the Polymarket bot guide. For programmatic access and building fee-aware strategies, the Polymarket API guide covers direct integration with the venue.