Positive Predictive Value Calculator

About this calculator

From a 2×2 confusion matrix of true positives (TP), false positives (FP), true negatives (TN) and false negatives (FN), this calculator derives four core diagnostic metrics: positive predictive value PPV = TP/(TP+FP) — the chance a positive result is really positive; negative predictive value NPV = TN/(TN+FN); sensitivity (recall) = TP/(TP+FN); and specificity = TN/(TN+FP).

Unlike sensitivity and specificity, PPV and NPV shift with how common the condition is in the population being tested, which is exactly why they matter in practice. Clinicians and epidemiologists use PPV to judge how much to trust a positive screening result in a given patient population, while data scientists use the same 2×2 breakdown to evaluate a binary classifier's precision and decide whether it's reliable enough to deploy, especially on imbalanced datasets.