Probability Calculator

Combine the probabilities of two independent events. Free, private, and runs entirely in your browser.

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Enter values and press Calculate to see the result here.

How this is calculated

For independent events, the chance of both is P(A) × P(B). The chance of at least one is P(A) + P(B) − P(A and B).

P(A and B) = P(A) × P(B)

P(A or B) = P(A) + P(B) − P(A)P(B)

What are independent events? Events where one outcome does not affect the other, like two separate coin flips.

Can probability exceed 100%? No. Every probability is between 0% and 100%.