Implied Probability
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Implied probability is the win percentage suggested by a set of betting odds. It converts odds from formats like American (-110) or decimal (1.91) into a straightforward percentage that tells you how often a bet needs to win just to break even at those prices. This concept is foundational to +EV betting because comparing the implied probability to your own estimated true probability of an outcome reveals whether a bet offers positive expected value. If you believe an outcome is more likely than the odds suggest, you\'ve found an edge worth exploiting.
Example
-150 American odds imply a 60% win probability. If your analysis suggests the team actually wins 65% of the time, you have a 5% edge—a strong +EV opportunity. On the other side, +150 implies 40% probability. If you estimate the underdog wins 50% of the time, that\'s a massive 10% edge. In practice, edges this large are uncommon; most profitable bets have edges of 1-5%. The key skill is accurately estimating true probabilities and then systematically betting whenever your number meaningfully exceeds the implied probability.
Common Questions
How do I calculate implied probability?
How do I calculate implied probability?
For American odds the formulas are: Negative odds = odds / (odds + 100), Positive odds = 100 / (odds + 100). For decimal odds, simply divide 1 by the decimal number. Some examples: -110 = 110/210 = 52.4% implied probability, +200 = 100/300 = 33.3%, and decimal 1.50 = 1/1.50 = 66.7%. These calculations tell you the break-even win rate at those odds before accounting for any edge you might have. Our implied probability calculator handles these conversions instantly across all odds formats.
Why do implied probabilities add to over 100%?
Why do implied probabilities add to over 100%?
The amount by which the combined implied probabilities exceed 100% represents the vig, also known as the overround or juice. If both sides of a moneyline are -110, the implied probabilities are 52.4% + 52.4% = 104.8%. That 4.8% overround is the sportsbook's built-in profit margin—it's how they guarantee revenue regardless of the outcome. Different sportsbooks charge different amounts of vig, and shopping for the lowest vig across multiple books is one of the simplest ways to improve your long-term results.
How does implied probability relate to expected value?
How does implied probability relate to expected value?
Expected value quantifies the average profit or loss per bet over the long run, and implied probability is the key input in that calculation. If the implied probability from the odds is 52.4% but you believe the true probability is 57%, the difference represents your edge. You calculate EV as: (true probability x profit) minus (loss probability x stake). Positive EV means the bet is profitable over time. Without understanding implied probability, you have no way to determine whether any given bet offers value or is simply a losing proposition disguised by attractive odds.