Statistics

Probability Calculator

Compute simple probability, independent joint probability, or complement probability from the right setup.

Preparing Probability Calculator

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Input

Choose the probability type first, then enter the event counts or probability values that belong to that situation. You will see the result first and the step-by-step solution below.

Input summary

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Step by Step Calculation

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Calculate first and the full working will appear below automatically.

How to use Probability Calculator

Pick the probability scenario you are working with, and the calculator will apply the matching probability rule.

What this calculator is for

This calculator is for introductory probability questions involving single events, independent events happening together, or the complement of an event.

Tips

Use the simple-probability mode when you have favorable outcomes over total outcomes.
Only multiply probabilities directly when the events are independent.
A complement represents not happening, so it equals 1 minus the original probability.