Polymarket advertises "0% trading fees" — but that's not what a trade actually costs you. Enter your numbers below to see the real drag: spread, gas, on/off-ramp fees, and the opportunity cost of locked capital.
| Cost component | Amount | % of position |
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Want the full picture? Our Polymarket Fees Explained guide walks through every cost line by line with worked examples.
Polymarket genuinely charges 0% on trade execution — there's no maker/taker fee like a centralized exchange. But "0% fees" and "0% cost" are not the same thing. Five real costs sit between you and your net return:
Every market has a gap between the best buy and best sell price. When you take liquidity, you pay that gap. On a deep market like a major election it might be half a percent; on a thin, niche market it can be 6% or more. This is the single most underrated cost on Polymarket, and it scales with how illiquid your market is.
Unless you already hold USDC on Polygon, you pay to convert fiat into crypto. Card-based on-ramps like MoonPay run around 4%; Transak is a bit cheaper; moving funds through a regular exchange like Coinbase is closer to 1%. This is a one-time cost on the way in.
Polymarket runs on Polygon, where transaction fees are tiny — typically a fraction of a cent to a few cents. We model a small flat amount. It only becomes significant if you bridge funds to or from Ethereum mainnet, which we don't assume here.
This is the cost almost everyone ignores. While your money sits in a position waiting for a market to resolve, it isn't earning anything. If that same capital could earn ~4.5% a year in a risk-free instrument, then a six-month hold has a real opportunity cost of roughly 2.25%. The longer the hold, the bigger the drag.
Getting money back to your bank costs something too — about 1% via a slow ACH path, more for instant card withdrawals. If you keep winnings as USDC and redeploy them, this cost is zero.
Add those up and the "0% fee" platform can quietly cost you anywhere from under 2% to well over 10% of your position, depending on how you fund it, how thin your market is, and how long you hold. The calculator above shows you that number before you place the trade.
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