Odds to Probability
Enter odds as a:b, or a probability to reverse.
Result
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Enter numbers to see the result.
Implied probability
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One in X
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Formula: Odds a:b means a wins per b losses: P = a/(a+b). Reverse: odds = P : (1-P).
Convert odds to probability (and back): fractional odds like 3/1 become a clean percentage.
Enter odds as a:b, or a probability to reverse.
Enter numbers to see the result.
Odds of a wins to b losses describe a + b equally weighted outcomes, so the implied probability is a/(a+b). Enter the counts directly: odds of 1 win to 3 losses give 1/4 = 25%. Betting fractional odds like 3/1 mean 1 win per 3 losses, so enter a = 1, b = 3.
Convert every outcome's odds in a market to probabilities and add them: honest odds sum to 100%, but bookmakers' odds sum to more, often 105-110%. The excess is their margin, the overround.