Kalshi and Polymarket price converter
What odds does a Kalshi or Polymarket price really pay?
Convert a contract price
Enter the price in cents and the venue. You get the odds it really pays once the venue's taker fee is added, and the win chance you need to break even.
A contract on Kalshi or Polymarket US pays $1 if it wins, so its price in cents reads like a chance. The venue’s taker fee is added to what you pay, though, so the odds it really pays are shorter than the price suggests. On 100 contracts:
| Price | Venue | Fee | Cost each | Break-even | Decimal | American |
|---|---|---|---|---|---|---|
| 47c | Kalshi | $1.75 | 48.75c | 48.75% | 2.051 | +105 |
| 47c | Polymarket US | $1.73 | 48.73c | 48.73% | 2.052 | +105 |
| 47c | Kalshi (baseball) | $0.88 | 47.88c | 47.88% | 2.089 | +109 |
| 30c | Kalshi | $1.47 | 31.47c | 31.47% | 3.178 | +218 |
| 70c | Polymarket US | $1.46 | 71.46c | 71.46% | 1.399 | -250 |
Compare the American column with what a sportsbook offers on the same team before choosing where to bet: the cheaper-looking contract is not always the better price. The fee is largest near 50 cents and is charged on the whole order, so a small order pays more per contract. Arbitrage between the two, after fees →
Whether these sports contracts are legal is disputed state by state, and the answer can change with a court ruling. Check your own state before using either venue.
Where the number comes from
The worked example was computed by the same engine that prices bets, at the moment this page was built. None of it was typed in. The build fails if a figure appears here and not in the engine's own output. The calculator runs that engine, release 0.1.37, in your browser, and the build checks that it returns this example’s answers for this example’s inputs.