Odds converter
Type any format — probability, American, decimal, fractional, or a contract price in cents — and the rest update instantly. Built for people moving between sportsbooks and prediction markets.
Prediction market prices are probabilities with the house margin stripped out — YES and NO sum to about $1. Sportsbook odds don't: their implied probabilities add up to more than 100%, and the excess is the book's edge.
The four formats, and when each is used
| Format | Example (62%) | Where you meet it |
|---|---|---|
| Probability | 62% | Forecasting, research |
| Contract price | 62¢ | Polymarket, Kalshi |
| American | −163 | US sportsbooks |
| Decimal | 1.61 | Europe, exchanges |
| Fractional | 8/13 | UK, horse racing |
The conversion that actually matters
If you're comparing a sportsbook line to a prediction market contract, convert both to probability first. A −163 line and a 62¢ contract are the same claim — but the sportsbook version has margin baked into it, and the contract doesn't. That's frequently a two-to-four point difference in your favour on the exchange side, before fees.
Once both sides are in probability, the only question left is which number is closer to the truth. See the field guide to reading odds for where market prices drift away from real probability.
Common questions
How do I convert American odds to probability?
For negative odds: probability = |odds| / (|odds| + 100). For positive odds: probability = 100 / (odds + 100). A −150 line implies 60%; a +200 line implies 33.3%.
What does a prediction market price of 62¢ mean in betting odds?
62¢ is a 62% implied probability, which equals −163 in American odds and 1.61 in decimal odds. Prediction markets quote probability directly, which is why they're easier to compare across events.
Why don't prediction market prices include a bookmaker margin?
Sportsbook odds are shaded to build in a house edge, so the implied probabilities of both sides add up to more than 100%. On a prediction market, YES and NO sum to roughly $1 — the venue takes a fee instead of a margin.