Calculators

Probability Calculator

Combine event probabilities (AND, OR).

Probability of A (%)Probability of B (%)

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P(A ∩ B)

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P(A ∪ B)

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P(not A)

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P(not B)

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P(neither)

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P(A not B)

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P(A | B)

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P(B | A)

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P(A ∩ B) as odds

Results assume events A and B are independent — the outcome of one does not affect the other.

Probability of at least one success in repeated trials

With P(event) = %, over trials →—at least once

This free probability calculator finds the chance of single and combined events. Enter the probability of A and B as percentages to get P(A and B), P(A or B), the complements, and the probability that neither event occurs. It assumes the two events are independent. All calculations run in your browser.