Odds to implied probability converter
Pick the format and type the odds as shown, such as 2.50, 5/2 or +150, to see the probability they imply.
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How to use it
- Enter odds format and odds.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
First convert to decimal odds D, then implied probability = 1 ÷ D × 100. Fractional a/b: D = a/b + 1. American positive: D = 1 + A/100; negative: D = 1 + 100/|A|.
Example
Inputs: Odds format = Decimal (e.g. 2.50), Odds = 2.50. Result: Implied probability: 40%; Decimal odds: 2.5; Probability of not happening: 60%.
Limits and caveats
- The probability comes from the quoted price and includes the margin of whoever set it, so the outcomes of one event usually add up to more than 100%.
- It is not the true chance of the event and does not predict the result.
Questions about this tool
What is implied probability?
The chance the quoted odds reflect: decimal 2.00 means 50% and 4.00 means 25%.
Why do the probabilities add up to more than 100%?
The price setter adds a margin for itself, and the amount above 100% is that margin.
Do I need the + sign for American odds?
Not for positive numbers, but negative ones need the minus sign, such as −110.