Sensitivity & Specificity Calculator

About this calculator

This calculator finds a diagnostic test's sensitivity (the true positive rate, TP/(TP+FN) — the fraction of actually-positive cases the test correctly flags), specificity (the true negative rate, TN/(TN+FP) — the fraction of actually-negative cases it correctly clears), and overall accuracy from a 2×2 confusion matrix of true and predicted outcomes. High sensitivity means few real cases are missed; high specificity means few healthy people are falsely flagged — and the two typically trade off against each other depending on where a test's decision threshold is set.

Clinicians and epidemiologists use these figures to judge whether a screening test is reliable enough for a given disease's prevalence, medical device and lab-test manufacturers report them to regulators as part of validation, and public-health officials use them when deciding whether to roll out a mass-screening program. Data scientists building machine-learning classifiers use the exact same math — under the names recall and true-negative rate — to evaluate model performance, and biostatistics students use this calculator to work through confusion-matrix problems.