Probability Calculator
Probability measures how likely an event is, from 0 (impossible) to 1 (certain). Enter how many outcomes are favorable and how many are possible to get the chance as a decimal, a percentage and a fraction.
Your numbers
Result
- As a decimal
- 0.17
- As a fraction
- 1/6
- Chance it does NOT happen
- 83.33%
| Step | Detail |
|---|---|
| Favorable outcomes | 1 |
| Possible outcomes | 6 |
| Fraction | 1/6 |
| Probability | 16.6667% |
How to calculate it
When outcomes are equally likely, probability is favorable / possible. Rolling a 6 on a die is 1 favorable outcome out of 6, so 1/6 = 0.167 = 16.7%. The value always sits between 0 and 1 (0% and 100%).
Combined events
For two independent events to both happen, multiply their probabilities (two heads in a row: 1/2 x 1/2 = 1/4). For either of two mutually exclusive events, add them. The chance an event does not happen is 1 - p, often the easiest route.
Frequently asked questions
Sources
- Probability (favorable over possible outcomes)
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