Prediction market payout calculator
Enter a contract price and your stake. Get payout, net profit after fees, ROI and the win rate you actually need to break even — with Kalshi's real fee formula applied.
Prediction market contracts settle at $1 or $0 — there is no partial outcome. A losing position loses everything you paid for it.
How the math works
A contract is a claim on $1. Its price is the market's probability estimate: 28¢ means "the market thinks this happens 28% of the time." Buy 100 contracts at 28¢ and you pay $28; if the event happens you receive $100.
That asymmetry is why price and probability are the same conversation. Your edge is not "will this happen" — it's "does it happen more often than the price implies, after fees."
Kalshi's fee formula
Kalshi charges 0.07 × contracts × price × (1 − price), rounded up to the next
cent, on taker orders. Because the formula multiplies price by its complement, the fee is
largest on coin-flip markets and smallest at the extremes:
| Price | Taker fee per contract | Maker fee per contract |
|---|---|---|
| 5¢ | 0.34¢ | 0.09¢ |
| 25¢ | 1.32¢ | 0.33¢ |
| 50¢ | 1.75¢ (maximum) | 0.44¢ |
| 75¢ | 1.32¢ | 0.33¢ |
| 95¢ | 0.34¢ | 0.09¢ |
Maker orders — resting limit orders that add liquidity — pay 25% of the taker fee. On balanced markets that difference is roughly 1.3¢ per contract, which is often larger than the edge itself.
Why break-even probability matters more than payout
A 3.5× payout looks impressive until you notice it corresponds to a 28% break-even rate. The question is never "how much could I win" — it's whether your estimate of the probability beats the price by more than the fee. That gap is what FluxrBot measures a thousand times a day across live news feeds.
Common questions
How is profit calculated on a prediction market?
Each contract settles at $1 if the event happens and $0 if it doesn't. If you buy at 28¢, every contract returns 72¢ profit on a win and loses the 28¢ you paid on a loss. Profit = contracts × (1.00 − price) minus fees.
How much does Kalshi charge in fees?
Kalshi's taker fee is 0.07 × contracts × price × (1 − price), rounded up to the next cent. The fee peaks at 50¢ (1.75¢ per contract) and shrinks toward both extremes. Maker orders pay 25% of the taker fee.
Does Polymarket charge trading fees?
Polymarket does not charge a percentage trading fee on most markets; your cost is the spread plus network gas. Select this venue in the calculator to model that case.
What is break-even probability?
It is the win rate you need for the trade to be neutral over many repetitions. At a price of 28¢ with fees included, you need to win slightly more than 28% of the time to break even.