Probability Calculator
Calculate the probability of an event given its favorable and total possible outcomes.
Calculate
Enter your values below.
Result
Probability
0
As a percentage
0
Formula used
P(event) = Favorable outcomes ÷ Total outcomes
Example: 3 favorable of 6 total (e.g. rolling ≤3 on a die) → probability = 0.5 (50%).
How to use this calculator
- Enter Favorable outcomes, Total possible outcomes.
- Press Calculate to see your result instantly.
FAQ
Frequently asked questions
Can favorable outcomes exceed total outcomes?
No — favorable outcomes must be less than or equal to the total, otherwise the input isn't valid.
What does a probability of 1 mean?
The event is certain to happen.
What does a probability of 0 mean?
The event cannot happen.
How do I combine two independent probabilities?
Multiply them together for 'both happen', or use P(A)+P(B)-P(A)×P(B) for 'at least one happens'.