Odds Format Guide
Decimal Odds
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.
American / Moneyline Odds
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.
Fractional 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.
Implied Probability
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.
FAQ
What does implied probability mean?
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.
Why do bookmakers' implied probabilities add up to more than 100%?
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%.
How do I convert American odds to decimal?
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.