Probability Calculator
Solve single event, two-event, and conditional probability problems with formulas shown.
About the Probability Calculator
What is Probability?
Probability measures the likelihood of an event occurring, expressed as a number between 0 (impossible) and 1 (certain). It is fundamental to statistics, finance, science, and decision-making.
How to Use
Select a tab based on your problem type. Enter probabilities as decimals between 0 and 1. The calculator displays results and the formulas used.
What is the difference between independent and mutually exclusive?
Independent events do not affect each other. Mutually exclusive events cannot happen at the same time, so P(A AND B) = 0.
What does P(B | A) mean?
P(B | A) is the conditional probability of B occurring given that A has already occurred.
Can I enter percentages instead of decimals?
Enter decimals (e.g., 0.5 for 50%). If you enter a value greater than 1, the calculator assumes it is a percentage and divides by 100.
Is this calculator free?
Yes, BestCalc's probability calculator is completely free with no ads or registration required.