Bayes' Theorem Calculator
Result
Bayes' Theorem Calculator Apply Bayes' theorem to update a probability in light of new evidence. Enter the prior probability of an event, the chance of the evidence when the event is true, and the chance of the evidence when it's false. The calculator ret — free online calculator.
Formula
- Bayes' Theorem Calculator calculates its result from P(A), P(B|A), P(B|not A). It uses the formula pBgA*pA/(pBgA*pA+pBgNotA*(1-pA)). Change any input to recalculate the result instantly.
- The main inputs are P. Enter them in the units and format shown in the calculator.
- Keep comparable quantities in compatible units whenever the formula combines or compares them.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Bayes' Theorem
- P: 0.3 A
- P: 0.8 B|A
- P: 0.2 B|not A
Using P(A) = 0.3, P(B|A) = 0.8, P(B|not A) = 0.2, the calculated result is 0.6315789474.
Sample result: Calculating…
Frequently asked questions
What does the Bayes' Theorem calculate?
Bayes' Theorem Calculator Apply Bayes' theorem to update a probability in light of new evidence. Enter the prior probability of an event, the chance of the evidence when the event is true, and the chance of the evidence when it's false. The calculator ret — free online calculator.
Which values should I enter?
Enter P using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: pBgA*pA/(pBgA*pA+pBgNotA*(1-pA)).
Why might my result differ from another source?
Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.