Probability Calculator
Calculate basic probability, combinations, permutations, and binomial distributions
Event Outcomes
Example: Rolling a die and getting a number ≤ 3 → favorable = 3, total = 6
Result
Enter values and click Calculate
About Probability
Combinations vs Permutations
Combinations count selections where order doesn't matter (e.g., choosing a team). Permutations count arrangements where order matters (e.g., rankings, passwords). C(n,r) ≤ P(n,r) always.
Binomial Distribution
Models the number of successes k in n independent trials each with probability p. Formula: P(X=k) = C(n,k) × p^k × (1−p)^(n−k). Mean = np, Variance = np(1−p).