Prediction Market Fee Calculator

Why fees matter more than they look

No prediction market is free to trade, and a fee of a cent or two per contract sounds trivial — but it raises your true break-even win rate. A 60¢ contract normally needs to win 60% of the time to break even; add a 1¢ fee and that climbs to 61%. For an active trader that gap compounds across hundreds of trades. This calculator shows your net profit and effective break-even after both a per-contract fee and an optional percentage fee on winnings, so you can compare the real cost of trading on different platforms.

Comparing platforms

Because fee structures vary so widely, the fairest comparison is the all-in cost on the markets you actually trade. The lowest-cost venues are covered in our lowest-fee platforms roundup, and every platform’s model is explained in its review — for example Kalshi fees or Robinhood fees. To factor fees into a single trade’s payoff, use the profit calculator; to judge whether a trade is worth it at all, the EV calculator.

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Frequently asked questions

How do prediction market fees work?

Fee models vary: some platforms charge a small per-contract fee, some take a percentage of winnings, and some bake a margin into the prices you trade at. This calculator lets you enter a per-contract fee and a percentage fee to see the combined effect.

How do fees affect break-even?

A fee raises your true break-even win rate. A 60-cent contract normally needs to win 60% of the time to break even; add a 1-cent fee and it needs about 61%. For active traders, that gap compounds across many trades.

Which platform has the lowest fees?

It depends on the markets you trade, since structures differ widely. Our lowest-fee platforms roundup compares the cheapest venues, and every platform's fee model is explained in its review.