Probability of an Event Calculator
🎲 Statistics & probability. Use the Probability of an event formula to find probability, ways it can happen, total equally likely outcomes: pick the value you want, type the others, and the answer updates as you go.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Probability | no unit |
| Ways it can happen | no unit |
| Total equally likely outcomes | no unit |
Worked example
Find the probability when Ways it can happen = 13, Total equally likely outcomes = 52.
Using P(A) = (ways it can happen)/(total outcomes): Probability = 0.25.
Frequently asked questions
What is the formula for Probability of an event?
P(A) = (ways it can happen)/(total outcomes).
What do the letters stand for, and what units are used?
Probability, Ways it can happen, Total equally likely outcomes.
How do you calculate probability?
Put the values into P(A) = (ways it can happen)/(total outcomes). For example, with Ways it can happen = 13, Total equally likely outcomes = 52, probability = 0.25.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (probability, ways it can happen, total equally likely outcomes) and fill in the others: it rearranges the formula for you.
