Probability Calculator

Your details

Choose what you want to calculate.
Probability that event A occurs (0 to 1).
Probability that event B occurs (0 to 1). Assumed independent of A.
ProbabilityModerate
58%

The main result for the selected calculation type.

P(A'): complement of A0.6%
P(B'): complement of B0.7%
P(A and B): both occur12%
P(A or B): at least one occurs58%
P(A xor B): exactly one occurs46%
P(neither): neither occurs42%
58%
Very unlikely<5%Unlikely5%-25%Moderate25%-75%Likely75%-95%Very likely95%+
Both (A and B)12%
At least one (A or B)58%
Exactly one46%
Neither42%

P(A or B) = 58.00% - at least one event will occur with this probability.

  • Both events together (A AND B) have probability 12.00% = 0.4 x 0.3, because A and B are assumed independent.
  • Exactly one of the two events occurs with probability 46.00%.
  • Neither event occurs with probability 42.00% = (1 - 0.4) x (1 - 0.3).

Next stepIf the two events are NOT independent, you need the conditional probability P(A|B) to compute the joint probability P(A and B) = P(A|B) x P(B).

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