How to convert prediction market prices to American odds
An event contract pays $1 if it wins, so its price in cents is the market's implied probability: a 62 cent contract is a 62% chance. To turn that into American odds, compare what you risk with what you win. Under 50 cents the odds are positive: +100 x (100 - price) / price. Over 50 cents they are negative: -100 x price / (100 - price). So 62 cents is -163.16, 38 cents is +163.16, and 50 cents is +100, even money.
Decimal odds are 1 divided by the price in dollars (62 cents = 1.613), and fractional odds are the profit over the stake (38/62, which reduces to 19/31). The calculator above does all of it exactly, both ways: switch to American odds to see what -150 or +130 costs in cents.
Worked examples at Kalshi's taker fee
Pre-game prices, before any per-order round-up. The last two columns are what you are really getting once Kalshi's taker fee is in the price.
| Price | Implied | American | Decimal | Fractional | American after Kalshi fee | Break-even after fee |
|---|---|---|---|---|---|---|
| 10¢ | 10% | +900 | 10.000 | 9/1 | +840.73 | 10.63% |
| 25¢ | 25% | +300 | 4.000 | 3/1 | +280.05 | 26.31% |
| 38¢ | 38% | +163.16 | 2.632 | 31/19 | +152.21 | 39.65% |
| 50¢ | 50% | +100 | 2.000 | 1/1 | -107.25 | 51.75% |
| 62¢ | 62% | -163.16 | 1.613 | 19/31 | -175.10 | 63.65% |
| 75¢ | 75% | -300 | 1.333 | 1/3 | -322.16 | 76.31% |
| 90¢ | 90% | -900 | 1.111 | 1/9 | -967.24 | 90.63% |
At 62 cents the fee adds about 1.65 cents a contract, so the real price is -175.10 and you need to win 63.65% of the time to break even, not 62%. The fee is largest in the middle of the range and shrinks toward 1 and 99 cents, because it scales with price x (1 - price).
Buying YES vs buying NO
Every contract has two sides. If YES trades at 62 cents, the mirror price of NO is 38 cents: the same market seen from the other side, at +163.16 before fees. Tap "The other side (NO)" to price it. On a live market the best NO offer is often a cent or two above the mirror because of the spread, so when you can see the actual NO offer, enter that price instead.
How exchange fees change your odds
A sportsbook builds its margin into both sides of the line. An exchange or prediction market lets you trade near the market price and charges a fee instead, and that fee is what turns a fair looking price into a worse one. The fee model here is the one every Wise Guy Team tool uses:
- Kalshi: Kalshi taker fee: 0.07 x price x (1 - price) per contract, before the per-order round-up to the cent.
- Polymarket US: Polymarket US taker fee: 0.0695 x price x (1 - price) per contract.
- Novig: no fee on pre-game straight trades. Live and futures: Novig publishes a taker fee our tools do not net yet, so the calculator shows those prices before fees.
- ProphetX: 2% of net winnings.
- No fee (sportsbook price or maker order): the bare price, for a sportsbook line or an exchange order that rests on the book (maker orders are priced differently from taking the offer).
Pick "No fee" to see the bare price, and run any two-sided sportsbook line through the no-vig calculator to find its fair price for comparison. New to the terms? Read what vig is.
Why 50 cents is both +100 and -100
American odds switch sign at even money. +100 means you win $100 on a $100 stake; -100 means you risk $100 to win $100. They are the same bet, which is why a 50 cent contract shows +100 here. Once a fee is added, the price moves to the minus side (for example about -107 at Kalshi's taker fee), because you now risk more than you win.
Related tools
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Frequently asked questions
How do you convert Kalshi prices to American odds?
A Kalshi price in cents is the market's implied probability: 62 cents means 62%. Under 50 cents, American odds = +100 x (100 - price) / price. Over 50 cents, American odds = -100 x price / (100 - price). So 62 cents is -163.16 and 38 cents is +163.16, before fees.
What is 50 cents in American odds?
+100, which is even money. At exactly 50% the two signs mean the same price: -100 and +100 both risk $100 to win $100. Any fee on top moves it to the minus side.
How do Kalshi fees change the odds?
Our tools use Kalshi's published taker fee: 0.07 x price x (1 - price) per contract, with price in dollars. At 62 cents that is about 1.65 cents a contract, which turns -163.16 into about -175. Kalshi rounds the fee on each order up to the cent, so a small order can cost slightly more. Resting (maker) orders are priced differently; pick No fee to see the bare price.
What is the price of the NO side?
The mirror of the YES price is 100 minus it: if YES is 62 cents, the other side is 38 cents, or +163.16. On a live market the best NO offer is usually a little higher than the mirror because of the bid and ask spread, so enter the price you can actually buy when you have it.
Is a prediction market price the true probability?
No. It is the price the market is trading at, and it carries a spread plus any fee. Compare it with a fair, no-vig price built from the sportsbooks before you call it value; the no-vig calculator and the +EV board do that.
Is this calculator a Wise Guy Team pick?
No. It does math on a price you enter and makes no prediction. Our documented plays are posted separately, and every one is tracked win or loss.
21+ (or the legal age where you live). Gambling problem? Call 1-800-GAMBLER. This calculator does arithmetic on prices you enter; it is not betting advice and not a Wise Guy Team play. Exchange fees and rules are set by each exchange and can change, so confirm the price and fee before you trade. Wise Guy Team is not a sportsbook or exchange and does not accept wagers. See our responsible gambling page.