✓ Effortless Math · Free Tool

Probability Calculator

Find the probability of a single event as a reduced fraction, decimal, and percent (with its complement), or combine two independent events to get P(A and B), P(A or B), and neither — with full step-by-step working.

Single event:  P = favorable ÷ total  ·  Two events:  P(A and B) = P(A)·P(B)
favorable ÷ total

Total must be greater than 0, and favorable can't exceed total. Whole numbers work best (e.g. 3 out of 6).

P(A) , P(B)

Enter each probability as a number from 0 to 1 (e.g. 0.5 for 50%). Events are assumed independent.

Results

Probability
—
—

Visual

Step-by-step