Probability Calculator

Calculate complement, union, intersection, and conditional probability of events.

Enter probability between 0 and 1 (e.g., 0.3 = 30%).
Enter probability between 0 and 1.
Independent: A does not affect B. Mutually exclusive: A and B cannot both occur. Custom: provide P(A∩B).

Results

Formulas Used

P(A′) = 1 − P(A)
P(A∪B) = P(A) + P(B) − P(A∩B)
P(A|B) = P(A∩B) / P(B)
References: Kolmogorov axioms. Addition rule: P(A∪B) = P(A)+P(B)−P(A∩B). Independent: P(A∩B) = P(A)×P(B). Conditional: P(A|B) = P(A∩B)/P(B).