Type odds in any format — decimal, American, or fractional — and all three update instantly.
Used in Europe, Australia, and Canada. The number represents your total return per unit staked (including stake). Odds of 2.50 on a $100 bet returns $250 ($150 profit + $100 stake). Decimal odds are always above 1.0.
Used in the United States. Positive odds (+150) show profit on a $100 stake. Negative odds (-200) show how much you must stake to profit $100. The favourite always has negative odds.
Traditional UK format. The fraction represents profit relative to stake. Odds of 3/2 mean $3 profit for every $2 staked. "Evens" (1/1) means you double your money.
The win percentage implied by the odds. Decimal: 1 ÷ odds × 100. American (+): 100 ÷ (odds + 100) × 100. American (−): |odds| ÷ (|odds| + 100) × 100. If your estimated probability exceeds the implied probability, you have a positive expected value bet.
Implied probability is the bookmaker's built-in estimate of how likely an outcome is to occur. Odds of 2.00 (decimal) imply a 50% probability. Odds of 3.00 imply 33.3%. If you believe the true probability is higher than the implied probability, the bet has positive expected value.
The excess over 100% is the bookmaker's margin (also called "vig" or "juice"). For example, on a coin-flip market, a bookmaker might offer 1.90 on both sides — each implying 52.6%, totalling 105.2%. The 5.2% is their edge. Our arbitrage calculator helps you find situations where the total implied probability is below 100%.
Positive American (+X): decimal = (X ÷ 100) + 1. Example: +150 → (150 ÷ 100) + 1 = 2.50. Negative American (−X): decimal = (100 ÷ X) + 1. Example: −200 → (100 ÷ 200) + 1 = 1.50.
In 2026, a common mistake is comparing books using rounded implied probabilities from odds converters. Tiny rounding differences (for example 52.4% vs 52.6%) can hide whether a bet is actually +EV after margin and exchange commission. Convert odds, then remove the bookmaker overround before comparing prices across sportsbooks or to a betting exchange. If you use an exchange, also recalculate after commission—2% to 5% can flip a seemingly better decimal price into the worse option.