Bayes' Theorem Calculator
Calculate conditional probability using Bayes' Theorem.
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- Instant Results
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Understanding This Calculator
Bayes' Theorem Formula
Calculates the probability of an event based on prior knowledge.
P(A|B) = [ P(B|A) × P(A) ] / P(B)
- P(A): Prior Probability (Base rate)
- P(B|A): Likelihood (True Positive Rate)
- P(B): Evidence (Total positive rate)
Example 1 (Medical Test)
Disease (A) affects 1% (0.01). Test accuracy (B|A) is 99% (0.99). Total positive rate (B) is 5% (0.05).
- P(A|B) = (0.99 × 0.01) / 0.05 = 0.0099 / 0.05 ≈ 0.198 (19.8%)
How to Use
- Enter prior probability P(A).
- Enter likelihood P(B|A).
- Enter evidence P(B).
Frequently Asked Questions
How do I use the Bayes' Theorem Calculator?
Enter your values in the input fields, and the result will appear instantly.
Is this calculator free to use?
Yes, this calculator is 100% free and does not require any registration or subscription.
Is it mobile-friendly?
Absolutely! Our tool is optimized for all devices, including mobile phones, tablets, and desktop computers.