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Last updated: August 2026

Polymarket Fees Explained

On Polymarket the headline fee is rarely your largest cost. Most of what a trade actually costs you is the spread you cross to get filled, plus slippage if your order is bigger than the top of the book, plus network transaction costs for moving funds. Traders who optimise only the stated fee usually leave more than that on the table in slippage.

01.The four costs, in the order they usually matter

Ranking them is more useful than listing them, because the ranking is stable even when the numbers change. On thin markets — which is most of them away from the headline questions — the spread and slippage dominate everything else by a wide margin.

  • Spread: the gap between bid and ask. Cross it on entry and again on exit, and you have paid it twice.
  • Slippage: what your order costs beyond the top of book when it eats into deeper levels.
  • Network transaction costs: paid when funds move on-chain, independent of trade size.
  • Platform fees: whatever the venue currently charges — check the source, since this changes.

02.Why the spread is the real fee

A market quoted 33c bid / 36c ask has a three-cent spread. Buying at 36 and later selling at 33 loses nine percent of your stake to the spread alone, before you are right or wrong about anything. That is a far bigger number than any percentage fee, and it is entirely within your control: post a limit order and you may collect the spread instead of paying it.

  • Round-tripping a three-cent spread on a 35c contract costs roughly 9% of stake.
  • Limit orders let you earn the spread rather than pay it, at the cost of an uncertain fill.
  • Wide spreads are a signal about liquidity, not just a cost — treat them as information.

03.Slippage scales with your size, not the market's

The quoted price applies to whatever quantity sits at the top of the book, which on a quiet market can be small. Send an order larger than that and you walk up through worse and worse levels, and your average fill can land cents away from what you clicked. Always look at depth rather than the headline price before sizing.

  • The displayed price is for the top level only, not for your whole order.
  • Depth, not price, tells you what a position will actually cost.
  • Splitting a large order across time or price levels is the standard mitigation.

04.Costs that are not fees at all

Two more sit outside the fee schedule and catch people out. Capital tied up in a position until resolution has an opportunity cost, especially on long-dated markets. And moving funds in and out has its own on-chain cost, which makes frequent small deposits disproportionately expensive.

  • Capital locked until resolution cannot be deployed elsewhere.
  • On-chain transfer costs are flat, so many small movements cost more than one large one.
  • Both argue for fewer, larger, more considered positions.

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Frequently Asked Questions

What fees does Polymarket charge?▼
Check the current schedule at the source, since it changes. More usefully: the stated fee is rarely your biggest cost. The spread you cross plus slippage on thin markets typically exceeds it, often by a lot.
Why did I get a worse price than the one displayed?▼
The displayed price applies to the quantity resting at the top of the book. An order larger than that fills through deeper, worse levels, so your average price lands away from the quote. That is slippage, and it is the main hidden cost on thin markets.
How do I reduce trading costs on Polymarket?▼
Use limit orders so you earn the spread rather than pay it, check depth before sizing rather than trusting the top-of-book price, and consolidate deposits — on-chain transfer costs are flat, so many small movements cost disproportionately more than one large one.
Is it cheaper than a sportsbook?▼
Usually, because exchange prices do not carry a bookmaker's overround. Sportsbook odds across all outcomes typically sum to well over 100%, and that excess is the house margin. To compare honestly, sum the implied probabilities on both.
Do I pay gas on every trade?▼
Network costs apply when funds move on-chain rather than on every order match. That is why frequent small deposits are inefficient and why consolidating movements matters more than optimising per-trade.