Probability Calculator

CaliforniaCalculator.net

Compare event relationships or model repeated independent trials.

Event probabilities

Results

Both A and B12%

Exactly one46%

Neither42%

P(A|B)40%

P(B|A)30%

Not A60%

Calculation breakdown

Independent events: P(A and B) = P(A) x P(B) = 40% x 30% = 12%.
P(A or B) = P(A) + P(B) - P(A and B) = 58%.
P(exactly one) = P(A only) + P(B only) = 46%.
P(neither) = 1 - P(A or B) = 42%.

How events A and B overlap

See the overlap as a concept map, then compare all four possible outcomes by their calculated share. The intersection represents both events occurring, while the non-overlapping regions represent only A or only B. The area outside both circles represents neither event and completes the sample space.

A40%

B30%

A and B12%

A or B58%

Concept map - circle area is not proportional

Both A and B12%

46% exactly one event42% neither event

Event outcome probability values
Outcome	Probability
A only	28%
Both A and B	12%
B only	18%
Neither	42%

Probability has no metric or imperial unit. Results are displayed to 2-3 decimal places and depend on the relationship or trial assumptions selected.