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PREDICTION MARKET TOOLS

Prediction Market Odds Converter

Convert probability, contract price, decimal odds and American odds. See what a quoted price means before fees.

One price, three ways to read it

Implied probability before fees or bookmaker margin.

Probability / price
40.00% / 40.00¢
Decimal odds
2.500
American odds
+150

Probability, price and odds

A binary contract that pays $1 and trades at 40¢ has a price-implied probability of 40%. That corresponds to decimal odds of 2.50 and American odds of +150, before fees. At 75%, decimal odds are about 1.333 and American odds are −300.

Decimal odds include the returned stake. Positive American odds express profit on a $100 stake; negative American odds express the stake needed for $100 profit. Probabilities of exactly 0% or 100% do not produce finite, ordinary two-sided odds, so this tool accepts values strictly between them.

The conversion does not remove a bookmaker’s margin or account for order-book spread, liquidity, fees or the possibility that two markets have different resolution rules.