Probability Calculator
Calculate probabilities for two independent events — union, intersection, complements, and repeated trials.
Probability of Two Events
Enter P(A) and P(B) to find all related probabilities for independent events.
Probability Solver for Two Events
Provide any 2 values below to calculate the rest (independent events).
Probability of a Series of Independent Events
Key formulas
P(A∪B) = P(A)+P(B)−P(A∩B)
Probability of two events
Probability is a number between 0 and 1 representing the likelihood of an outcome. For independent events A and B, the probability of both occurring is the product of their individual probabilities.
The complement P(A') = 1 − P(A). XOR (exactly one event) is P(A Δ B) = P(A ∪ B) − P(A ∩ B).
Complement of A and B
P(A') is the probability that event A does not occur. P((A∪B)') is the probability that neither A nor B occurs — equal to 1 − P(A∪B).
Series of independent events
When the same independent event repeats n times, the probability of all occurring is Pn. Example: P(rolling 6 five times) = (1/6)5.