Enter odds in any format — American, Decimal, Fractional, or Implied Probability — and get all four. The math is exact; the conversions are instant. No signup, no marketing.
American odds are the default in U.S. sportsbooks. A negative number (like -150) is how much you must risk to win $100; a positive number (+130) is how much you win on a $100 bet. The "100" is the reference unit, not necessarily what you'd actually bet.
Decimal odds are the European standard and the easiest for math. Decimal odds of 2.50 mean a winning $1 bet pays back $2.50 total ($1 stake + $1.50 profit). Decimal odds = profit-per-unit-stake + 1.
Fractional odds are the UK standard, common in horse racing. A fractional price of 7/2 means you win 7 units for every 2 you stake. Fractional odds = profit-to-stake ratio.
Implied probability is what the odds say the market thinks the outcome's chance is. Implied probability = 1 / decimal odds, expressed as a percentage. Two-way markets always sum to more than 100% because of the sportsbook's vig — see our No-Vig Calculator to strip that out.
Different books and markets quote in different formats. Live odds screens, futures markets, props, and international books often mix conventions. Converting to a common format — usually decimal for math, or implied probability for comparison to your model — is the first step in any disciplined bet evaluation.
Implied probability is the single most useful conversion. Comparing your model's win probability to the market's implied probability is how you spot edge. A +EV bet exists when your estimate beats the market's implied probability by more than the book's hold.