# Bayes Theorem Calculator

> Bayes theorem calculator: update a prior probability into a posterior using test sensitivity, specificity, and base rate for risk decisions. Free, no signup.

- **Canonical URL:** https://boringtoolskit.com/bayes-theorem-calculator/
- **Category:** Statistics
- **Evidence level:** catalogue
- **Reviewed:** July 26, 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

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