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Probability Calculator

Union, intersection, conditional.

Probability (independent A, B)

P(A ∩ B)
0.150000
Both events happen
P(A ∪ B)
0.650000
At least one happens
Exactly one
0.500000
A or B but not both
Neither
0.350000
1 − P(A ∪ B)
P(not A) / P(not B)
0.5000 / 0.7000
At least one in 1.5 trials on avg
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Probability Calculator · Generated 5/2/2026 · calccenter.online/calculators/math/probability

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About the Probability Calculator

MethodologyHome

Union, intersection, conditional. Use this free probability calculator to get instant results. All calculations run in your browser — nothing is sent to a server.

Frequently asked questions

What does this Probability Calculator do?

Union, intersection, conditional.

Is it free?

Yes — every calculator on Calc Center is free, with no sign-up or account required.

Does it work offline?

The site is a Progressive Web App — after your first visit, most pages work without an internet connection.