Implied Probability Calculator
Implied Probability Results
Implied Probability
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Decimal Odds
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Fractional Odds
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American Odds
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Potential Return
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Market Analysis
Total Probability
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Overround
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Fair Odds
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Bookmaker Margin
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Implied probability is the conversion of betting odds into a percentage that represents the bookmaker's estimated chance of an outcome occurring.
Implied probability helps you identify value bets. If you believe the true probability is higher than the implied probability, you may have found a value betting opportunity.
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Bookmakers never offer "Fair Odds." If a coin flip has a 50% chance, the fair odds are 2.00 (+100). A bookmaker will offer you 1.91 (-110) on each side. That difference is the "Overround," also known as the "Vigorish" (Vig) or "House Edge." It is the fee the bookmaker charges for facilitating the bet.
To find the house edge embedded in any market, convert the odds into implied probabilities and sum them. Anything above 100% is the bookie's guaranteed profit margin.
(Where \(o_i\) represents the decimal odds for each outcome)
For a standard two-way market where both sides are priced at 1.91, the implied probability for each is \(1/1.91 = 52.36\%\). The sum is \(104.72\%\), meaning the overround is \(4.72\%\).
Professional bettors use the overround calculation to "de-vig" a line. By removing the margin, you can estimate the market's consensus "Fair Price" for an outcome.
Different bookmakers apply different overrounds. Sharp books like Pinnacle operate with margins as low as 2–3%, while soft books might have margins of 5–8% on the same market.
| Bookmaker Type | Typical Overround | Impact on Bettor |
|---|---|---|
| Sharp Book | 2% - 3% | Minimal barrier; closest to "true" market odds. |
| Soft Book | 5% - 8% | Significant barrier; requires a larger edge to profit. |
| Recreational Book | 8% - 12%+ | Extreme barrier; nearly impossible for long-term profit. |
A: Implied probability is the percentage chance of an outcome happening as suggested by the betting odds. It's calculated by converting odds into a probability percentage.
A: In a fair market, all probabilities should add up to 100%. If they add up to more than 100%, the difference is the bookmaker's margin (overround), representing their built-in profit.
A: A value bet occurs when you believe the true probability of an outcome is higher than the implied probability suggested by the odds. This means the odds are offering better value than they should.
A: Bookmakers adjust odds so that the total implied probability exceeds 100%. This excess (typically 2–10%) is their profit margin, ensuring they make money regardless of the outcome.