Math Calculators
Probability Calculator
Combine the probabilities of two events.
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About the Probability Calculator
Combine the chances of two events happening. Enter the probability of event A and event B and the calculator returns the probability of both happening (A and B), either happening (A or B), and A not happening — assuming the events are independent. It's a handy tool for statistics, games, and risk estimates.
How to use the Probability Calculator
- 01Enter your the probabilities of events A and B.
- 02Read the result instantly — it recalculates as you type.
- 03Adjust the numbers to model different scenarios.
Frequently asked questions
How do I combine probabilities?
For independent events, P(A and B) = P(A) × P(B), and P(A or B) = P(A) + P(B) − P(A and B).
What does 'independent' mean?
One event doesn't affect the other's probability — like two separate coin flips. This tool assumes independence.