What is Chi-Square Calculator?

Chi-Square Calculator performs chi-square goodness-of-fit and independence tests with full statistical output. Enter observed and expected frequencies, and get the chi-square statistic, degrees of freedom, p-value, and Cramer's V effect size. Includes a visual chi-square distribution curve showing your result.

How to use

1. Choose your test type: Goodness of Fit (one variable vs expected distribution) or Test of Independence (two categorical variables in a contingency table).
2. Enter your observed frequencies in the table cells. For goodness of fit, also enter expected frequencies. For independence, the expected values are calculated automatically.
3. Click Calculate to see the chi-square statistic, degrees of freedom, p-value, and whether to reject the null hypothesis at your chosen significance level (0.01, 0.05, or 0.10).

Result

A marketer tests whether 4 ad variants perform equally. Observed clicks: A=142, B=186, C=121, D=151. Expected: 150 each. The chi-square test yields X2=14.2, df=3, p=0.0026 — significant difference, Variant B wins.

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