Statistics calculator
Probability Calculator
Calculate independent probability for A and B, A or B, and not A.
Formula
Independent probability
P(A and B) = P(A) x P(B); P(A or B) = P(A) + P(B) - P(A and B)
If A is 40% and B is 30%, both happen with 12% probability.
FAQs
Does this assume independence?+
Yes. It assumes event A and event B are independent.
What if events are not independent?+
Use conditional probability instead; this simple calculator will not model dependence.
How does the Probability Calculator calculate the result?+
It uses the Independent probability: P(A and B) = P(A) x P(B); P(A or B) = P(A) + P(B) - P(A and B). If A is 40% and B is 30%, both happen with 12% probability.
What information do I need to use the Probability Calculator?+
Calculate independent probability for A and B, A or B, and not A.
How accurate is the Probability Calculator?+
Probability Calculator applies the formula and assumptions shown on this page. Results may be rounded for readability, so verify changing rates, thresholds, medical guidance, or legal rules with the cited source or a qualified professional.
What should I check before using the Probability Calculator result?+
Check that the units, dates, rates, and assumptions match your situation. Change one input at a time to understand which values have the largest effect on the result.
Statistics guide
How to use the Probability Calculator
Calculate independent probability for A and B, A or B, and not A. The page also explains the independent probability and shows a practical example: If A is 40% and B is 30%, both happen with 12% probability.
- 1
Enter your details
Enter the values for the probability calculator scenario you want to check.
- 2
Check the calculation
Review the result alongside the independent probability: P(A and B) = P(A) x P(B); P(A or B) = P(A) + P(B) - P(A and B).
- 3
Compare scenarios
Change one or more inputs to see how they affect the probability Calculator result before you use the estimate.
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