EVERYDAY CLARITY
Event Union Probability Calculator
Calculate the probability of either event using their supplied overlap.
Your result
Probability A or B occurs
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Probability of A | Enter probability of a using the definition in the method and example. |
| Probability of B | Enter probability of b using the definition in the method and example. |
| Probability of both | Enter probability of both using the definition in the method and example. |
Understanding your result
These outputs describe the probability model and event definitions you entered. A probability is a number from 0 to 1; a probability density is not itself the probability of one exact continuous value.
Common mistakes
- Entering 25 instead of 0.25 for a probability, or assuming events are independent when the model requires that assumption.
- Confusing an exact-count probability with a cumulative probability, or replacement with sampling without replacement.
Check your calculation
- Check a zero/certain-event boundary and the stated support of the distribution against the worked example.
Calculation checks, sources and review limits
What is the chance A or B occurs when they may overlap?
Calculate the probability of either event using their supplied overlap.
Common uses
- What is the chance A or B occurs when they may overlap
How it works
union = a + b - joint
Worked example
Enter Probability of A: 0.3 ; Probability of B: 0.4 ; Probability of both: 0.1 . Results: Probability A or B occurs: 0.6 .