Implied Probability Calculator
Convert betting odds to implied probability and identify value bets by comparing with your own probability estimate.
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How to use this calculator
Implied probability is the market's estimate of an outcome's chance of happening, expressed as a percentage. Comparing it with your own estimate reveals whether the odds offer value.
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Select the odds format your sportsbook uses.
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Enter the odds for the selection you are evaluating.
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Enter your own estimate of the outcome's probability.
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Read the implied probability, value bet status, and expected value.
Frequently asked questions
What is a value bet?
A value bet occurs when you believe the true probability of an outcome is higher than the probability implied by the odds. If you think a team has a 60% chance of winning and the odds imply 50%, you have a 10% edge — this is a value bet.
What is expected value in betting?
Expected value (EV) is the average profit or loss per bet over a large number of bets. Positive EV means you profit on average; negative EV means you lose. Finding consistently positive EV bets is the basis of professional sports betting.
What is the overround / vig?
If you add the implied probabilities of all outcomes in a betting market, the total exceeds 100%. This excess is the bookmaker's margin, called overround or vig. A typical market has a 2–10% margin built in, which is why casual bettors lose money in the long run.
Implied Probability Calculator — Find Value Bets & Expected Value
Implied Probability Formulas by Odds Format
Decimal: probability = (1 / decimal) × 100. American positive: 100 / (odds + 100) × 100. American negative: |odds| / (|odds| + 100) × 100. All give the same result for equivalent odds.
How to Use Implied Probability to Find Value
Research the true probability of an outcome using statistics, historical data, or expert analysis. If your estimated probability exceeds the implied probability in the odds, the bet offers positive expected value. The larger the gap, the greater the edge.
Why Most Bettors Lose
The bookmaker's margin means implied probabilities always sum to more than 100%. Without a genuine edge — meaning bets with positive EV — bettors will lose at the rate of the margin over time. Professional bettors win by consistently finding markets where the odds misprice the true probability.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →