Prediction-market odds converter

Turn a Kalshi or Polymarket contract price in cents into American, decimal and fractional odds and back. Add the other side's price to see the spread and the fair price.

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Every Kalshi, Polymarket and exchange price in our tools is also shown at its net price after fees.

Open the Odds Screen Learn how it works

How it works

A prediction-market contract pays $1 if it wins. Its price in cents is the break-even chance, and converting it to sportsbook odds is one division:

decimal = 100 ÷ cents · implied = cents ÷ 100

American: decimal 2.00 or more → +100 × (d − 1); below 2.00 → −100 ÷ (d − 1)

The two sides of a market each have their own price to buy. If Yes costs 55¢ and No costs 47¢, the pair costs 102¢ for a $1 payout: that 2¢ is the spread, the market's equivalent of a sportsbook's vig. The fair price sits in the middle, (55 + 100 − 47) ÷ 2 = 54¢, which is how our tools devig exchange prices.

Worked example

Yes at 55¢ is decimal 100 ÷ 55 = 1.8182, which is −122.2: you need to win 55% of the time to break even before fees.

With No at 47¢: the pair costs 102¢ for a $1 payout → spread 2¢

Fair Yes = (55 + 100 − 47) ÷ 2 = 54¢ → fair odds −117.4

Price	American	Decimal	Implied
5¢	+1900	20.000	5.00%
10¢	+900	10.000	10.00%
20¢	+400	5.000	20.00%
25¢	+300	4.000	25.00%
33¢	+203	3.030	33.00%
40¢	+150	2.500	40.00%
45¢	+122.2	2.222	45.00%
50¢	+100	2.000	50.00%
55¢	−122.2	1.818	55.00%
60¢	−150	1.667	60.00%
67¢	−203	1.493	67.00%
75¢	−300	1.333	75.00%
80¢	−400	1.250	80.00%
90¢	−900	1.111	90.00%
95¢	−1900	1.053	95.00%

Things to watch

Fees are extra. Kalshi and Polymarket US charge a fee on top of the price; see the fee calculator for your net price.
The price you see may not fill. Only the shares offered at that price are available; a bigger order fills worse.
Last trade is not a price. Use the price you can buy at now (the ask), not the last traded price.

Frequently asked questions

How do I convert cents to American odds?

Divide 100 by the price to get decimal odds, then convert. 40 cents is decimal 2.50, which is +150; 60 cents is decimal 1.667, which is -150.

What does a 55 cent contract mean?

You pay 55 cents for a contract that pays $1 if it wins, so you need to win more than 55% of the time to profit before fees.

Why do Yes and No add up to more than $1?

Each side is the price someone will sell at. The amount over $1 is the spread, which plays the role of a sportsbook's vig.

Do these odds include fees?

No. The converter turns a price into odds. Exchange and prediction-market fees lower your real price; the fee calculator shows the net price for each venue.

Related calculators

Exchange and prediction-market fee calculatorNet price after Kalshi, Polymarket, ProphetX, Novig and exchange fees.Implied probability calculatorBreak-even win % for any price; add the other side for the no-vig fair.Odds converterAmerican, decimal, fractional, probability, HK, Malay, Indonesian.No-vig fair odds calculatorFair odds with five devig methods side by side, 2- to 6-way markets.

Learn more

Exchange fees: your net price on Kalshi, Polymarket, Novig and moreExchanges charge fees instead of building vig into the price. Here's how each venue's fee changes the odds you actually get.Intro to +EV bettingPositive expected value means a price pays more than its fair odds. Here's how to find the fair odds and what the edge really means.