Sensitivity and Specificity Calculator
Calculate sensitivity, specificity, PPV and NPV for a diagnostic test from its true/false positive and negative counts.
About the Sensitivity and Specificity Calculator
Sensitivity and specificity describe how well a diagnostic test tells the sick from the healthy. Sensitivity is the share of people who truly have the condition that the test correctly flags as positive; specificity is the share of people who don't have it that the test correctly flags as negative.
Formula: Sensitivity = TP ÷ (TP + FN) · Specificity = TN ÷ (TN + FP) · PPV = TP ÷ (TP + FP) · NPV = TN ÷ (TN + FN)
Enter the four counts from a test's confusion table to see all four metrics at once. A highly sensitive test rarely misses true cases, while a highly specific test rarely raises false alarms — real-world screening tools usually trade one off against the other.