Free tool
Odds converter: American, decimal, fractional & prediction-market
Convert between American (moneyline), decimal (European), fractional odds, and prediction-market prices in real time. A Kalshi or Polymarket price in cents reads straight as an implied probability.
Odds converter
Edit any field and the rest update live. Kalshi / Polymarket quote in cents (a 53¢ price = 53% implied ≈ −113).
How to use it
Type a value into any field, American, decimal, fractional, or a prediction-market cents price, and every other field updates at once. There's no convert button; the fields stay in sync as you type.
Why the formats differ
American odds (-110, +150) are the US standard; decimal (1.91) is used across Europe and most exchanges; fractional (10/11) is the UK tradition. They all encode the same payout, only the notation differs. A prediction-market price (53 cents) is already an implied probability, which is why it converts cleanly to about -113 American.
Frequently asked
What are American odds?
American odds use positive and negative numbers. A negative number (e.g. -110) shows how much you must bet to win $100. A positive number (e.g. +150) shows how much you win on a $100 bet. -110 is the standard vig line at most sportsbooks.
How do I convert a prediction-market price to betting odds?
A prediction-market price is already an implied probability. A Kalshi or Polymarket price of 53 cents means a 53% chance, which equals about -113 in American odds and 1.89 in decimal. Enter the cents price and the converter returns the American, decimal, and probability equivalents instantly.
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