📊Chi-Square Test Calculator
Run goodness-of-fit and independence tests with full per-cell working.
Enter observed and expected frequencies (one row per category)
Free Chi-Square Test Calculator
Testing whether your data fits an expected pattern, or whether two categorical variables are related? Our free chi-square test calculator handles both goodness-of-fit and independence (contingency table) tests, giving you the chi-square statistic, degrees of freedom, and p-value instantly.
For goodness-of-fit, enter your observed and expected frequencies; for independence, build a contingency table and the expected frequencies are calculated automatically from the row and column totals. Every cell's contribution to the chi-square statistic is shown, so you can see exactly where the biggest deviations come from, not just the final number.
Built for statistics coursework, survey analysis, and research. No sign-up, no downloads, completely free.
About the Chi-Square Test Calculator
Features
Two test modes
Goodness-of-fit and independence, each with its own input layout.
Dynamic contingency table
Flexible row and column counts for common table sizes.
Per-cell working
Every category or cell's contribution to χ² shown individually.
Accurate p-value
Computed from the chi-square distribution CDF across arbitrary degrees of freedom.
Frequently Asked Questions
What's the difference between goodness-of-fit and independence tests?
Goodness-of-fit checks whether observed frequencies match an expected distribution; independence checks whether two categorical variables are related, using a contingency table.
How is the chi-square statistic calculated?
By summing (observed − expected)² / expected across all categories or cells.
How are expected frequencies found in an independence test?
From (row total × column total) / grand total for each cell, computed automatically from your entered data.
How are degrees of freedom determined?
k − 1 for goodness-of-fit with k categories; (rows − 1) × (columns − 1) for an independence test.
What does a significant result mean?
For goodness-of-fit, that observed data significantly deviates from the expected distribution; for independence, that the two variables are likely related, not independent.
What size contingency table can I use?
The tool supports flexible row/column counts for common table sizes.
What if an expected frequency is zero?
Expected frequencies must be greater than zero for the chi-square formula to be valid; the calculator flags this case.
Does it show the per-cell working?
Yes, each category or cell's contribution to the chi-square statistic is shown individually.
Is my data stored?
No, everything runs client-side in your browser.
Is it free?
Yes, completely free with no sign-up or limits.