# ROC Curve and AUC Calculator

> Free ROC curve and AUC calculator. Paste test values and 0/1 labels and get the area under the curve with a DeLong 95% confidence interval, the best cut-off by the Youden index with sensitivity, specificity and likelihood ratios, a sentence for your manuscript and R code. Runs in your browser.

Canonical: https://biostatkit.com/roc-auc

Paste the test value and the true condition (1 or 0) of each person and get the ROC curve, the area under it (AUC) with its 95% confidence interval, the best cut-off by the Youden index with the sensitivity, specificity and likelihood ratios there, a sentence you can paste into your manuscript, and the R code that reproduces the numbers.

## Methods wording

The ROC curve and the area under it were calculated with BiostatKit [1]. The 95% CI of the AUC used the method of DeLong et al [2], and the optimal cut-off was the value with the highest Youden index.

Method: empirical ROC curve, AUC with DeLong 95% CI, cut-off by the Youden index, Wilson and log-method CIs at the cut-off.

## Frequently asked questions

### What is a good AUC?

There is no fixed threshold. 0.5 means no better than a coin toss and 1 means perfect separation. Look at the 95% confidence interval and at what the test is for: an AUC of 0.75 can be useful for screening and too low to confirm a diagnosis.

### Which cut-off should I choose?

The Youden cut-off treats a missed case and a false alarm as equally bad. If missing the condition costs more, pick a cut-off with higher sensitivity on clinical grounds and say so. Report whether the cut-off was set in advance (STARD item 12a).

### How are tied values handled?

A tie between a person with and a person without the condition counts as half a win, as in the Mann-Whitney statistic. A rating scale with a few levels gives a curve with only a few points.

### Can I compare two tests here?

No. Comparing two AUCs measured on the same people needs the paired DeLong test, which this page does not run.

### Is my data stored or sent anywhere?

No. All calculations run in your browser tab. Nothing is uploaded, and the page works offline once loaded.

## Related calculators

- [Sensitivity and specificity calculator](https://biostatkit.com/sensitivity-specificity)
- [Cohen's kappa](https://biostatkit.com/cohens-kappa)

Author: TS.BS. Vũ Duy Kiên (https://www.vuduykien.com)