Bayes' Theorem
Calculate conditional probabilities using Bayes' theorem
Clinical Test Scenario
Posterior Probability
P(A|B) = 16.10%
A positive test means ~16.1% chance you have the condition
1.00%
95.00%
5.00%
83.90%
Bayes' Theorem
P(A|B) = P(B|A) × P(A) / [P(B|A) × P(A) + P(B|¬A) × P(¬A)]
About Bayes' Theorem
Bayes' theorem describes the probability of an event based on prior knowledge of conditions that might be related to the event. It is fundamental in statistics, machine learning, and diagnostic testing.
P(A|B) = P(B|A) × P(A) / [P(B|A) × P(A) + P(B|¬A) × P(¬A)]
Where:
• P(A|B) is the posterior probability of A given B
• P(A) is the prior probability of A
• P(B|A) is the likelihood (true positive rate / sensitivity)
• P(B|¬A) is the false positive rate (1 — specificity)
The Sensitivity/Specificity mode models a clinical test scenario where prevalence, sensitivity, and specificity are given as percentages. The calculator automatically computes the false positive rate and applies Bayes' theorem.
Save Configuration Snapshot
Save current parameters to your dashboard for instant one-click reloading.
About This Calculator & Guide
About the Bayes' Theorem Calculator
The Bayes' Theorem Calculator is a specialized online utility designed to help you calculate conditional probabilities using bayes' theorem. prior and posterior probability calculator with sensitivity and specificity. It performs calculations in real-time to provide immediate, reliable estimates for study, work, or daily tasks.
How to Use
Simply enter your parameters in the input fields of the calculator widget above. The tool evaluates the inputs instantly and displays the results in real-time. You can modify any value to check alternate scenarios and compare figures dynamically.
Data Privacy & Safety
All calculations are executed locally within your web browser. No inputs are sent to our servers or stored externally, ensuring your personal and financial details remain completely private and secure.
FAQ
Frequently Asked Questions
What does the Bayes' Theorem Calculator do?+
Calculate conditional probabilities using Bayes' theorem. Prior and posterior probability calculator with sensitivity and specificity. It is designed for quick everyday use and gives clear results without requiring a sign in.
Is the Bayes' Theorem Calculator free to use?+
Yes. The Bayes' Theorem Calculator is free to use online and works directly in your browser.
Can I use the Bayes' Theorem Calculator on mobile?+
Yes. The calculator layout is responsive, so you can use it on phones, tablets, laptops, and desktop screens.