Example: P(A): 30% · P(B): 50% · A and B are: Independent → P(A and B): 15%.
P(A or B): 65%
P(not A): 70%
P(neither): 35%
Frequently asked questions
How do I calculate probability? Enter your numbers above and the result updates instantly. For example: P(A): 30% · P(B): 50% · A and B are: Independent → P(A and B): 15%.
Is this Probability Calculator free? Yes — completely free with no sign-up or paywall. It runs entirely in your browser and keeps working offline; the numbers you enter never leave your device.
How accurate is it? It uses the standard published formula for probability. Results are estimates for planning — not financial, tax, medical, engineering, or legal advice.