Sensitivity and Specificity Calculator
Calculate sensitivity, specificity and predictive values from a diagnostic test's 2×2 table.
Predictive value depends on prevalence, and that surprises people
A test with 99% sensitivity and 99% specificity sounds excellent. Apply it to a condition affecting 1 in 10,000 and a positive result is still wrong about 99 times out of 100, because false positives from the vast healthy majority swamp the handful of true cases. Sensitivity and specificity are properties of the test; predictive value is a property of the test *and* the population.
What this page needs from you
This page asks for true positives, false negatives, true negatives and false positives. From those it returns sensitivity in %, together with specificity, positive predictive value, negative predictive value and accuracy. Every figure updates as you type, and nothing you enter leaves your browser.
Significance is not the same as importance
With a large enough sample almost any difference becomes statistically significant, because significance measures how confident you can be that a difference exists at all — not how big it is or whether it matters. Effect size answers the second question, and the two should always be read together.
The formula
Sensitivity = TP/(TP+FN); specificity = TN/(TN+FP)
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Sensitivity and Specificity Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Sensitivity and Specificity Calculator — frequently asked questions
Is this sensitivity and specificity calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the sensitivity and specificity calculator.
- sensitivity and specificity calculator
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- true positive rate
- diagnostic test accuracy
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed September 14, 2026 · Calculation runs client-side · No data collected · Report an error