Sensitivity Calculator

What Is Test Sensitivity?

Sensitivity is the proportion of diseased people who test positive. It is also called the true positive rate. High sensitivity helps rule out disease when the test is negative. Related tools: Sensitivity and Specificity Calculator and Post-Test Probability Calculator.

Sensitivity Formula

$$Sensitivity = \frac{TP}{TP + FN}$$

$TP$ is true positives and $FN$ is false negatives. The denominator is everyone who actually has the disease, regardless of test result.

Sensitivity vs Specificity

Sensitivity focuses on diseased patients. Specificity focuses on healthy patients who correctly test negative. A test can have high sensitivity but still produce many false positives if specificity is low. Use both metrics together.

Example

If 86 diseased patients test positive and 14 diseased patients test negative, sensitivity is $86/(86+14) = 0.86$, or 86%.