Calculadora de Sensibilidade e Especificidade
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Sens = TP/(TP+FN); Esp = TN/(TN+FP)
About this calculator
This online calculator determines the sensitivity and specificity of a diagnostic test from the values of true positives (TP), true negatives (TN), false positives (FP), and false negatives (FN). Sensitivity measures the proportion of true positives among all diseased individuals, while specificity measures the proportion of true negatives among all non-diseased individuals. These indicators are essential for evaluating test accuracy in fields such as medicine, biology, and health sciences.
The operation is simple: enter the four values in the corresponding fields and click Calculate. The formula uses the counts of TP and FN for sensitivity (TP / (TP + FN)) and TN and FP for specificity (TN / (TN + FP)). The result is displayed as a percentage, making interpretation easy. For example, a sensitivity of 95% means the test correctly detects 95% of actual positive cases.
Use this calculator when analyzing the effectiveness of a new diagnostic test, comparing different methods, or evaluating the performance of a clinical exam. It is useful for researchers, healthcare professionals, and students who need to validate tests. Remember that sensitivity and specificity are independent of disease prevalence, but interpretation should consider the clinical context.
Caution: extreme values can occur with small samples. Ensure data are accurate and representative. The calculator does not replace a full statistical analysis but provides a quick and reliable calculation for these basic indicators.
Frequently asked questions
What does 100% sensitivity mean?
A test with 100% sensitivity detects all diseased individuals, meaning there are no false negatives. This is ideal for screening serious diseases.
What is the difference between sensitivity and specificity?
Sensitivity measures the ability to correctly identify diseased individuals (true positives), while specificity measures the ability to correctly identify non-diseased individuals (true negatives).
Can I use the calculator for tests with more than two outcomes?
No, this calculator is designed only for binary tests (positive/negative). For continuous or multiple outcomes, use ROC curves.
How do I interpret low sensitivity values?
Low sensitivity indicates many false negatives, meaning the test fails to detect many diseased individuals. This can lead to missed diagnoses.
What if one of the values is zero?
If TP+FN is zero, sensitivity is undefined (division by zero). Check your data: it may mean there are no diseased individuals in the sample. The same applies to specificity if TN+FP is zero.