Chi-Square Calculator

Compare observed and expected counts to get a chi-square statistic, degrees of freedom and a p value.

Chi-square test

Degrees of freedom

Chi-square statistic: —

Degrees of freedom: —

P value: —

Critical value at 5 percent: —

Largest contribution: —

Enter the counts in matching order. Every expected count should be greater than zero for the test to be valid.

Type the observed counts into the first box, separated by commas.
Type the expected counts into the second box in the same order.
Read the chi-square statistic, degrees of freedom and p value in the result panel.

Common questions about the free online chi-square calculator.

Enter your observed counts and the expected counts in matching order, and the statistic, degrees of freedom and p value appear.

It sums, over every category, the squared difference between the observed and expected counts divided by the expected count.

For a goodness of fit test they equal the number of categories minus one, and they set the shape of the chi-square curve.

A small p value means the observed counts differ more from the expected counts than chance alone would usually explain.

When the p value is below 0.05, the usual cut off, the difference is called statistically significant at the 5 percent level.

It is the chi-square value that leaves 5 percent of the curve in the upper tail for your chosen degrees of freedom.

The formula divides by each expected count, so a zero makes the statistic undefined, and tiny counts make the test unreliable.

It names the category whose observed count differs most from its expected count, showing which group drives the statistic.

No. Every calculation runs locally in your browser, so your numbers never leave your device.

Yes. It is completely free and unlimited, with no account, no sign-up and no usage limits of any kind.

Last updated: October 10, 2026