Implied Probability Calculator
Turn any odds into the probability they imply — and compare it with your own estimate to see whether a price offers value.
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Quick answer
Implied probability = 1 ÷ decimal odds. Odds of 4.00 imply a 25% chance. If your own, well-researched estimate is higher than the implied probability, the price may offer value — but the bookmaker’s margin means implied probabilities are slightly inflated.
Implied Probability Calculator
Free · no sign-up · calculates as you type
- Definition Implied probability
- The chance of an outcome suggested by its price, including the bookmaker’s margin. Across all outcomes in a market, implied probabilities add up to more than 100%.
Using your own estimate
Enter your own probability to see the fair odds for that estimate, your “edge” against the price in percentage points and the expected value of the bet. Expected value is a long-run average across many similar bets — it does not tell you what will happen next.
Frequently asked questions
How do you calculate implied probability?
Divide 1 by the decimal odds and multiply by 100. For fractional odds a/b, it is b ÷ (a + b).
Why do implied probabilities add up to more than 100%?
Because the bookmaker builds a margin (the overround) into every market.