Probability Calculator

Use our free probability calculator to compute P(A), P(not A), P(A and B), P(A or B), and P(A|B) for independent events.

Math

Rule

P(A)

P(B)

P(A and B)

Formula

Compute basic probability rules for independent events: single, complement, joint (and), union (or), and conditional probability.

P(not A)=1-P(A), P(A&B)=P(A)×P(B), P(A|B)=P(A&B)/P(B)

Percentage: The percentage value you want to apply

Number: The original number or value

Result: The calculated result

How It Works

1Select the probability rule.
2Enter the probability value(s) (0 to 1).
3Click Calculate.

Examples

P(A)=0.5, P(B)=0.3: P(A and B)

1.P(A and B) = 0.5 × 0.3 = 0.15

Result: 0.150000

P(A)=0.5: P(not A)

1.P(not A) = 1 - 0.5 = 0.5

Result: 0.500000

Frequently Asked Questions

A measure between 0 and 1 of how likely an event is to occur.

P(A and B) = P(A) × P(B) for independent events.

P(A or B) = P(A) + P(B) - P(A and B).

P(A|B) = P(A and B) / P(B), the probability of A given B.

P(not A) = 1 - P(A).

Related Calculators

Binomial Distribution Calculator Poisson Distribution Calculator Combination Calculator Permutation Calculator Percentage Calculator Basic Calculator

CalculateMe Team

Last updated: 2026-07-14

Probability Calculator

Formula

How It Works

Examples

P(A)=0.5, P(B)=0.3: P(A and B)

P(A)=0.5: P(not A)

Frequently Asked Questions

What is probability?

P(A and B) for independent?

P(A or B) formula?

What is conditional probability?

What is complement?

Related Calculators

Probability Calculator

Formula

How It Works

Examples

P(A)=0.5, P(B)=0.3: P(A and B)

P(A)=0.5: P(not A)

Frequently Asked Questions

What is probability?

P(A and B) for independent?

P(A or B) formula?

What is conditional probability?

What is complement?

Related Calculators