Odds Converter — American, Decimal & Fractional
American odds are the default at every US sportsbook, but decimal and fractional notation show up constantly — European books quote decimal, UK-influenced markets use fractional, and analysts talk in implied probability. This odds converter translates between all four instantly, with no rounding surprises, and shows the equivalents as you type.
How the conversion works
positive American: decimal = 1 + odds / 100 (+150 → 2.50) negative American: decimal = 1 + 100 / |odds| (-200 → 1.50) fractional: numerator/denominator = decimal − 1 implied probability = 1 / decimal
Reference table
American Decimal Fractional Implied win % +150 2.50 3/2 40.00% +100 2.00 1/1 50.00% -110 1.91 10/11 52.38% -200 1.50 1/2 66.67%
Reading each format
- American: positive = profit on a $100 bet; negative = stake needed to profit $100.
- Decimal: total return per $1 staked, stake included.
- Fractional: profit relative to stake — 3/2 wins $3 for every $2 wagered.
- Implied probability: the win chance the price needs to break even, before removing the sportsbook’s margin.
New to American odds? Read the guide on how to read American odds, then try the betting odds calculator to turn any price into a payout.
FAQ
What's the difference between American, decimal, and fractional odds?
They're three ways of quoting the same payout. American odds show how much you win on a $100 bet (or how much you need to bet to win $100). Decimal odds show your total return per $1 staked, including your stake. Fractional odds show your profit as a ratio to your stake — 3/2 means you win $3 for every $2 wagered.
How is implied probability calculated?
Implied probability is 1 divided by the decimal odds, shown as a percentage. It's the win probability the odds represent before accounting for the sportsbook's built-in margin (the vig).
Why don't the implied probabilities on both sides of a game add up to 100%?
Because the book bakes in a margin, called the vig or juice. Add up the implied probability of both sides of a two-way market and you'll typically get somewhere around 104-107%, not 100%. Our no-vig calculator strips that margin out, and the vig calculator measures it.
Why can’t American odds be between -100 and +100?
American odds are quoted as the amount you risk to win $100 (negative) or win on $100 (positive), so even money is +100 and the numbers jump straight from -100 to +100. Anything in between has no valid meaning, which is why this calculator rejects it.
What is -110 in decimal odds?
-110 is 1.9091 in decimal (1 + 100/110), 10/11 in fractional, and a 52.38% implied probability.
Are the conversions exact?
Yes. Everything is calculated at full precision and rounded only for display. Fractional odds use the simplest exact fraction, so -110 shows as 10/11 rather than a rounded 91/100.