Sensitivity & Specificity Calculator
Evaluate diagnostic test performance using true positives, false positives, true negatives, and false negatives. Widely used in medical research, diagnostics, and screening test validation.
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How the Sensitivity & Specificity Calculator Works
Sensitivity and specificity are two of the most important metrics used to evaluate the performance of diagnostic tests in healthcare and biomedical research. Sensitivity measures how effectively a test identifies individuals who truly have a condition, while specificity measures how effectively it identifies individuals who do not have the condition. These values help clinicians and researchers understand the strengths and limitations of medical tests, screening tools, and laboratory assays.
This calculator uses four fundamental values: true positives (TP), false positives (FP), true negatives (TN), and false negatives (FN). These values come from validation studies or clinical trials where the performance of a diagnostic tool is compared against a gold standard. Sensitivity is calculated by dividing TP by the total number of people who actually have the condition (TP + FN). Specificity is calculated by dividing TN by the total number of non-diseased individuals (TN + FP). The calculator also provides positive predictive value (PPV) and negative predictive value (NPV), which reflect how well the test performs in real-world settings where disease prevalence may vary.
Accuracy provides an overall measure of how often the test gives the correct result, combining both positive and negative classifications. While accuracy is useful, sensitivity and specificity offer deeper insight into test reliability, especially for diseases with low or high prevalence. Understanding these metrics is essential for medical practitioners, epidemiologists, diagnostic manufacturers, and researchers who interpret test results or develop new diagnostic technologies.
This tool is designed for educational and research purposes and runs entirely in your browser without storing any data. It provides a quick and transparent way to compute key diagnostic metrics using simple input fields. Whether you're evaluating a new medical test, reviewing research data, or learning how diagnostic accuracy works, this calculator offers a reliable starting point for analysis.
Frequently Asked Questions
What is sensitivity?
Sensitivity measures how well a test identifies individuals who truly have the condition. A highly sensitive test has few false negatives.
What is specificity?
Specificity measures how well a test identifies individuals who do not have the condition. A highly specific test has few false positives.
What are PPV and NPV?
PPV (Positive Predictive Value) measures the probability that a positive test result is correct. NPV (Negative Predictive Value) measures the probability that a negative test result is correct.
Does this tool store my data?
No. All calculations run locally in your browser. No information is saved or transmitted.