Diagnostic Accuracy Calculator
Check sensitivity, specificity, and predictive-value denominators using aggregate test counts.
Your entries stay in this page’s memory and are not submitted to us. Downloads are generated locally. Reloading or leaving the page clears your entries. Do not enter patient information.
Calculate descriptive diagnostic proportions from a single threshold and reference standard. Use one independent observation per participant. Defaults are fictional; this is not a tool for diagnosing an individual.
Calculation results
- Sensitivity
- 80%
- Specificity
- 85%
- Positive predictive value
- 72.7273%
- Negative predictive value
- 89.4737%
- Reference-positive proportion in this sample
- 33.3333%
Confidence intervals are not calculated. Predictive values depend on the sampled population and cannot automatically be transferred to another setting.
Denominators matter
Sensitivity = TP/(TP+FN); specificity = TN/(TN+FP); PPV = TP/(TP+FP); NPV = TN/(TN+FN). A zero denominator is displayed as not estimable. Unverified, indeterminate, or missing reference results require explicit handling and cannot simply be treated as negatives. Case-control diagnostic sampling usually prevents direct interpretation of predictive values as those in clinical practice.
FDA: reporting diagnostic test studies · Read the practical guide · Download blank worksheet (TXT)