Free tool
Odds Converter — Probability, Decimal, American
Type into any field and the others update. Prediction markets quote in cents of a dollar, sportsbooks in decimal, fractional or American — these are all the same number wearing different clothes.
Implied probability
25.0%
Fractional odds
3/1
What these mean
- Implied probability is the honest form: 25% means the market prices this at one chance in four.
- A prediction-market contract that pays $1 on success simply trades at the probability — 25c is 25%. That is why these markets are easier to read than a bookmaker's line.
- A bookmaker's quoted odds add up to more than 100% across all outcomes. That excess is their margin, so converting a sportsbook price gives you their number, not a fair probability.
- American odds are the awkward one: +300 means stake 100 to win 300, while -300 means stake 300 to win 100. The sign flips at even money.