Probability Calculator

Probability of single events plus union/intersection and complement for two events.

Calculator Numbers & Math Updated Apr 20, 2026
How to Use
  1. Enter favorable and total outcomes for A and B.
  2. Toggle independence for intersection formula.
Events
Result

Formulas

Single event
P(A) = favorable / total
Intersection
independent: P(A)·P(B) · else conditional
Union
P(A ∪ B) = P(A) + P(B) − P(A ∩ B)

Last updated: