Conditional Probability Calculator

Your details

Pick the data you have. All three modes produce the same conditional-probability outputs.
Probability that BOTH A and B occur. Must be between 0 and P(B).
Probability of event B occurring. Must be greater than 0.
Optional. P(A∩B̅). When provided, the calculator also outputs P(A|B̅), P(Ã|B), and P(Ã|B̅). Leave blank or 0 to skip.
P(A | B)Less likely
40%

Probability of A given that B has occurred.

P(A | B) decimal0.4
P(Ã | B)60%
P(A | B̅)11.43%
P(Ã | B̅)88.57%
P(B)30%
P(B̅)70%
IndependenceDependent
Posterior P(A|B)40%
40% %
Unlikely<25Less likely25-50More likely than not50-75Very likely75+

Given B, the probability of A is 40%.

  • Given that B occurred (P(B) = 30%), the probability of A is 40%.
  • P(A|B) = P(A and B) / P(B) = 0.4 in decimal form.
  • A and B are statistically dependent: knowing B changes the probability of A.

Next stepCompare P(A|B) with P(A|not-B) to see how strongly B separates the two cases.

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