Polymarket Fees: What a Trade Actually Costs

I put $5 into a Polymarket contract and took it back out an hour later. The market moved half a cent. I lost 12%.

Nobody hid anything from me. Every number was on the screen. But the charge that did most of the damage never appears with the word “fee” next to it, and I only found it by subtracting my own balance from itself.

The short answer

Polymarket charges a fee when you buy or sell at a price that is already sitting there. That is called a taker fee, and a market order is always a taker. Post your own price and wait for somebody to come to you, and you pay nothing.

The sum is:

fee = number of shares × rate × price × (1 − price)

That price × (1 − price) part decides everything. It makes the fee biggest at 50¢ and smallest at the two ends. Which means Polymarket charges you most for trading the questions nobody is sure about, and least for trading the ones already settled in everybody’s mind.

Nothing is taken to deposit, to withdraw, or when a market resolves.

The rates

Geopolitics carries no fee at all, so that is where to go if you want to learn the buttons without paying tuition. And crypto costs nearly twice what politics costs, on the same screen, with the same click.

What it came to on a real trade

A politics market at 18¢. I had exactly $5.00 in the account and put all of it in.

Afterwards my cash read $0.04, so $4.96 had gone. The position said Traded $4.80, which is 26.7 shares at 18¢. The 16 cents between those two numbers is the fee. Run the formula and it predicts 15.8 cents, so it matches.

An hour later I sold half. The dialog promised Receive $2.27. What landed was $2.19.

$2.48 in, $2.19 back, 29 cents gone, on a market that had moved half a cent. The spread accounts for less than half of that.

Three places the fee hides

None of these say “fee”. This is the part I’d want somebody to have told me.

In the average price. The buy button says Yes 18¢. Two lines down the panel says Avg. Price 19¢, and nothing explains the gap. At a flat 18¢ my $5 would have bought 27.8 shares. I got 26.7. The missing shares are the charge, taken out before the shares are counted.

In the word “Receive”. The sell dialog offered Receive $2.27. The button under it said Cash out $2.27. I received $2.19.

In the loss your portfolio shows you. Mine read minus 2.72% seconds after buying. Sell at that moment and I’d have been down 11.5%, four times worse. Three things stack up: the entry fee isn’t counted against the Traded figure it’s measured from, the Value column prices your shares halfway between the buy and the sell price where nobody can actually sell, and the exit fee hasn’t happened yet.

That last one is the one that costs people money, because Value looks exactly like a cash figure and behaves like an estimate.

The half that isn’t the fee

The rest of the round trip is the spread, paid going in and again coming out, and measured against the price you paid rather than against a dollar. A penny is 1% of a 90¢ contract and 20% of a 5¢ one.

Here’s the bit no fee page mentions. The smallest step a price is allowed to move is set market by market. On the one I traded it was a whole cent. On the 2028 presidential markets it’s a tenth of a cent. Same platform, same evening, ten times the difference in what the spread can cost you. On those markets the fee is more than nine tenths of your round trip and the spread is a rounding error.

So “check the spread” is half the advice. Check the step size and the category too.

Who is actually paying whom

Takers pay. Makers don’t, and on most categories they collect a share of what the takers paid.

Read that twice, because it describes the room. The beginner clicking the big blue button funds the person who posted the order that beginner just filled. That isn’t a scandal, it’s how every order book on earth pays for its own liquidity, and Polymarket is unusually open about the arithmetic. But it does mean the default behaviour of the interface is the expensive one, and the cheap one requires you to wait.

Money in, money out

Polymarket takes nothing at either end. That doesn’t make it free.

Sending USDC yourself costs a network fee, which on most chains runs from nothing to a few cents. Mine cost zero and arrived in about a minute.

The card is the expensive door. I put $100 through it and $96.20 arrived. The lines actually labelled “fee” came to $2.18. The rest was folded into an exchange rate that priced a dollar-pegged token at $1.02. Full breakdown in the funding guide.

Four ways to pay less

Post your price instead of taking one. A limit order resting on the book pays no fee and often earns a rebate. Biggest saving available, and it costs you nothing except patience.

Stay away from very cheap contracts. At 5¢ a round trip takes about a quarter of your stake before the market does anything at all.

Fund with crypto. Saves roughly 4% against the card.

Practise on geopolitics. No fee, so the lesson only costs you the spread.

What changed in March 2026

Trading on Polymarket was free until 30 March 2026. The current structure arrived in a single update.

Worth knowing because a lot of what’s written about Polymarket costs was accurate when it was published and isn’t now. Anything that tells you the platform charges nothing to trade was written before the spring.

What I think of it

The rates are fine. A tenth of a percent on a 90¢ contract is cheaper than most places you could put the same money, and paying makers out of taker fees is a reasonable way to keep the book deep enough to trade.

The labelling is the problem. Three different screens report your money, and not one of them uses the word. A trader who checks the fee page knows exactly what they’re paying. A beginner reading Avg. Price as a rounding artefact does not, and it’s the beginner who trades by market order and pays it every time.

FAQ

Nothing here is financial advice. Prediction markets involve real risk, so never trade money you can’t afford to lose.