Odds Converter — American, Decimal & Fractional
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American odds are the default at every US sportsbook, but decimal and fractional notations show up constantly — European books use decimal, UK-influenced markets use fractional, and props are sometimes quoted as an implied percentage. This tool converts between all four instantly, with no rounding surprises.
Worked example: +150 American odds equal 2.50 decimal, 3/2 fractional, and a 40.00% implied win probability. A $100 bet at +150 returns $250 total ($150 profit) if it wins.
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 (coming soon) strips that margin out.