# Cohen's Kappa Calculator

> Free Cohen's kappa calculator for two raters. Enter the agreement table (2 to 5 categories) and get kappa, weighted kappa, its 95% confidence interval, observed and expected agreement, a sentence for your manuscript and R code.

Canonical: https://biostatkit.com/cohens-kappa

Enter how two raters classified the same subjects and get Cohen's kappa with its 95% confidence interval, the observed and chance agreement, a sentence you can paste into your manuscript, and the R code that reproduces the numbers.

## Methods wording

Agreement between two raters was calculated with BiostatKit [1] as Cohen's kappa [2], with the 95% CI from the large-sample standard error of Fleiss, Cohen, and Everitt.

Method: Cohen's kappa (unweighted, linear or quadratic weights) with the Fleiss-Cohen-Everitt large-sample standard error.

## Frequently asked questions

### Weighted or unweighted kappa?

Use unweighted kappa when the categories have no order (diagnosis A, B, C). Use linear or quadratic weights when they are ordered (mild, moderate, severe), so that a one-step miss counts less than a two-step miss.

### Why is my kappa low when most ratings agree?

Kappa corrects for chance agreement, and when almost all subjects fall in one category the chance agreement is already high. Report the observed agreement and the counts as well.

### What is a good kappa?

Landis and Koch suggested 0.61 to 0.80 as substantial and above 0.80 as almost perfect, but they called their own bands arbitrary. Judge kappa against what your field needs and report its confidence interval.

### What about more than two raters?

This calculator is for exactly two raters rating the same subjects. For three or more raters use Fleiss' kappa or the intraclass correlation.

### 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

- [Intraclass correlation (ICC)](https://biostatkit.com/icc)
- [Bland-Altman analysis](https://biostatkit.com/bland-altman)
- [Sensitivity and specificity calculator](https://biostatkit.com/sensitivity-specificity)

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