Implied probability calculator: what the prices are saying
List every outcome in a market, such as each team's title price, each CPI range or cut, hold and hike. See how much the field adds up to over 100¢ and the cleaned-up probability of each.
Outcomes in the field (edit freely)
Exactly one outcome should settle yes. If the list leaves a gap, the total can fall below 100¢ without any mispricing.
Readout
| Outcome | Price | Implied | Normalized |
|---|---|---|---|
| A | 40¢ | 40.0% | 38.1% |
| B | 30¢ | 30.0% | 28.6% |
| C | 20¢ | 20.0% | 19.0% |
| D | 15¢ | 15.0% | 14.3% |
The field adds up to 105¢, 5¢ over 100. Dividing each price by the total gives a cleaner read of the market's view.
normalized probability = price ÷ field total
Worked example
Four outcomes trade at 40¢, 30¢, 20¢ and 15¢. Exactly one will settle yes, so fair prices would add up to 100¢. These add up to 105¢: a 5¢ overround, the field's built-in markup.
Divide each price by 105 to normalize it. The 40¢ outcome becomes about 38.1%, and the others 28.6%, 19.0% and 14.3%. It's a rough adjustment, because markup usually isn't spread evenly; cheap outcomes often carry more of it.
For a single price, implied probability is just the price in cents: 62¢ implies about 62%. To convert it to American or decimal odds, use the odds converter.
Questions
How do you calculate implied probability from a contract price?
A contract pays $1 if it settles yes, so its price in cents reads as a probability. A 62¢ price implies about 62%. Fees and the bid-ask spread make your real break-even a little higher.
What is overround?
How far the prices of a complete field add up above 100¢. If four outcomes trade at 40¢, 30¢, 20¢ and 15¢, they total 105¢, a 5¢ overround.
How do you remove the overround?
Divide each price by the field total. In a 105¢ field, a 40¢ outcome normalizes to about 38.1%. This is approximate, because markup is rarely spread evenly.
Why can a field add up to less than 100¢?
Usually because the listed outcomes don't cover every possibility, such as a missing range or no 'other' outcome. Check that the field is complete before reading the total.
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