Probability Calculator

Calculate probability for various scenarios including single events, multiple events, conditional probability, and complements

Probability Calculator

Probability Type

Favorable Outcomes

Total Possible Outcomes

Probability Formulas

Basic Probability

P(Event) =

Favorable Outcomes

Total Outcomes

Multiple Events

P(A and B) = P(A) × P(B) [Independent]

P(A or B) = P(A) + P(B) [Mutually Exclusive]

P(A or B) = P(A) + P(B) - P(A and B) [General]

Conditional Probability

P(A|B) =

P(A and B)

P(B)

Bayes' Theorem

P(A|B) =

P(B|A) × P(A)

P(B)

Key Rules

Range: 0 ≤ P(Event) ≤ 1

Complement: P(A') = 1 - P(A)

Certain event: P(Event) = 1

Impossible event: P(Event) = 0

Frequently Asked Questions

Probability measures the likelihood of an event occurring, ranging from 0 (impossible) to 1 (certain). Basic probability = favorable outcomes ÷ total outcomes. For example, the probability of rolling a 6 on a die is 1/6 ≈ 0.167 or 16.7%.

Tips

Enter the dimensions in the same unit for consistency.
Results update automatically as you type.
Use the unit selector to convert between different measurement systems.

Probability Calculator