Odds Converter

Sportsbooks publish the same price three or four different ways depending on the market. American odds dominate domestic books and use a plus or minus sign tied to a hundred-dollar reference — minus-150 means a bettor must risk a hundred fifty dollars to win a hundred, while plus-150 means a hundred dollars wins a hundred fifty. Decimal odds, common across European and Australian books and most exchanges, simply state the total return per unit staked. Fractional odds, the British tradition, express profit as a ratio. All four formats — including implied probability — describe one underlying number.

That underlying number is the decimal price. Converting between formats is mechanical once a price reaches decimal form. American to decimal divides the absolute value of negative odds into a hundred and adds one, or divides positive odds by a hundred and adds one. Fractional to decimal divides the numerator by the denominator and adds one. Implied probability to decimal is one divided by the probability. Going the other way reverses each step.

The reason to know all four is that they expose different things at a glance. American odds make payouts on a flat hundred-dollar stake easy to read. Decimal odds make multiplication across parlay legs trivial. Fractional odds make ratios clean, especially at longshot prices. Implied probability is the version that matters for evaluating a bet — it states the break-even win rate the price requires before any sportsbook margin or bettor edge is considered. A minus-110 price has an implied probability of 52.4 percent, which means a bet at that price has to hit better than 52.4 percent of the time to be profitable long term.

The converter above accepts any of the four formats as input and returns the other three instantly. It also shows the profit on a hundred-dollar stake, which is a useful sanity check when reading lines from a screen where the format is not labeled clearly.