Prediction markets
What a trade actually costs
The fee formula, what it does to your break-even, and why it bites hardest in the middle of the board.
Two costs sit between a good idea and a profit: the spread you cross to get filled, and the trading fee. The spread is set by the market. The fee is arithmetic, and it is worth knowing by heart.
The formula
The fee on a fill is 7% of price × (1 − price) per contract, rounded up to the next whole cent. Price is the contract's price as a probability, so a 40¢ contract is 0.40. That shape means the fee peaks in the middle of the board, at 50¢, and shrinks toward both ends.
| Price | Fee on 100 | Fee per contract | Break-even chance |
|---|---|---|---|
| 5¢ | $0.34 | 0.34¢ | 5.3% |
| 10¢ | $0.63 | 0.63¢ | 10.6% |
| 25¢ | $1.32 | 1.32¢ | 26.3% |
| 50¢ | $1.75 | 1.75¢ | 51.8% |
| 75¢ | $1.32 | 1.32¢ | 76.3% |
| 90¢ | $0.63 | 0.63¢ | 90.6% |
| 95¢ | $0.34 | 0.34¢ | 95.3% |
Read the last column as the real price of the trade. A contract quoted at 50¢ does not break even at a coin flip — it breaks even a little above one, and the difference is the fee. On a market you are trading because you think the price is a point or two off, that gap is most of your edge.
The two practical rules that fall out: trade nearer the ends of the board when the edge is the same, because the fee is smaller there, and count the round trip rather than the entry. A position you intend to close before resolution pays the fee twice and the spread twice.
The break-even calculator takes a price and tells you the win rate the fee demands.
Run your own numbersEvery figure on this page is read from our live plan catalog and from the engine’s own fee function at the moment the page loads. Accounts are simulated; the rules described here are the ones the engine enforces automatically.