Prediction market odds converter for Kalshi and Polymarket
Prediction markets such as Kalshi and Polymarket quote a contract as a price between 1¢ and 99¢. The contract pays $1 if the event happens, so the price is the market’s implied probability: 65¢ means 65%.
To compare that with a sportsbook you need it as odds. Enter the price and this converts it to American and decimal odds and shows what $100 returns.
How it works: Prediction market contracts trade between 0c and 100c. A "Yes" contract at 65c implies a 65% probability. Buying "No" at 65c is equivalent to betting the event won't happen at 35c (35% implied probability).
Free, no account needed. Everything is worked out in your browser and nothing you type is saved.
How to use the prediction market odds converter
- 1Enter the Yes price in cents, for example 65 for a 65¢ contract.
- 2Choose Yes or No. No is priced at 100 minus the Yes price, so a 65¢ Yes means No costs 35¢.
- 3Read the implied probability, the American and decimal odds, and the total payout for $100 spent.
- 4Compare those odds with a sportsbook’s price on the same outcome, allowing for the venue’s trading fee where there is one.
Worked example: Yes at 65¢
A contract on a team to win trades at 65¢.
- Implied probability (Yes)
- 65.0%
- American odds
- -186
- Decimal odds
- 1.54
- Payout on $100 of Yes
- $153.85
- No at 35¢
- +186, 2.86, $285.71
$100 at 65¢ pays back $153.85 if the team wins, before fees. Decimal odds are 1 ÷ 0.65 = 1.538, and as American odds that is -185.7, rounded to -186. The No side at 35¢ works the same way: 1 ÷ 0.35 = 2.857, or +186.
Frequently asked questions
How do I convert a Kalshi price to American odds?
Turn the price into a probability p (65¢ is 0.65). Above 50¢ the odds are negative: -100 × p ÷ (1 − p), so 65¢ is -185.7, about -186. At 50¢ or below they are positive: 100 ÷ p − 100, so 35¢ is +185.7, about +186.
Does the conversion include fees?
No, it converts the raw price. Kalshi charges a trading fee that varies with the price, and some Polymarket markets charge fees too, so the odds you actually get are slightly worse than shown. Check the venue’s fee schedule before comparing with a sportsbook.
What if the No price is not exactly 100 minus Yes?
On a live order book the best Yes and No asks usually add up to a little over 100¢; the difference is the spread. To price the No you would actually pay, enter that No ask as the price with Yes selected. The conversion is the same for either side.
Are prediction market odds better than sportsbook odds?
Sometimes. A liquid market often trades close to the fair price, while a sportsbook builds in a margin, so on popular games a contract can beat the book. Convert both to the same format and compare.
Free now, free for good
Every BreadSync calculator is free to use without an account, and that is not changing. They work on the odds you type in.
BreadSync Pro lists Kalshi, Polymarket and other prediction markets on the same odds screen as 130+ sportsbooks, already converted to odds.
Related calculators
- Odds ConverterConvert between American, decimal and fractional odds and implied probability.
- No-Vig CalculatorStrip the vig from a two-way market to get fair odds and win probability, four devig methods.
- Expected Value CalculatorCompare the odds you can bet with fair no-vig odds to see what a bet is worth on average.
- Arbitrage CalculatorCheck whether two or three prices are an arb and split your stake so every outcome pays the same.
21+. Worked examples are illustrative and use made-up prices; real odds change constantly. Calculator results are estimates for information only, not betting advice or a guarantee of profit. BreadSync is not a sportsbook and does not accept wagers. If gambling stops being fun, call 1-800-GAMBLER.