How do I enter probability?

As a decimal between 0 and 1 (e.g. 0.3 = 30%).

For two independent events both happening (AND).

A + B − A·B to avoid double-counting the overlap.

How does conditional work here?

Enter A as the joint P(A∩B) and B as the condition; result is A/B.

No — an educational tool for basic calculations.

Compute a single event, its complement, both events, either event, or a conditional probability.

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Last updated: 2026-06-03

This calculator uses generic assumptions. Use advanced mode to override them for a more accurate result.

Source: default

AND = A·B · OR = A+B−A·B · P(A|B) = P(A∩B)/P(B)

How do I enter probability?: As a decimal between 0 and 1 (e.g. 0.3 = 30%).
When to multiply?: For two independent events both happening (AND).
Either formula?: A + B − A·B to avoid double-counting the overlap.
How does conditional work here?: Enter A as the joint P(A∩B) and B as the condition; result is A/B.
Is this statistical consulting?: No — an educational tool for basic calculations.

Results are estimates and not professional advice. Verify important decisions with a qualified professional.