Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Chi-Square Test Calculator

Compute the chi-square test statistic contribution for one observed-vs-expected category pair using χ² = (observed − expected)² / expected. Sum these contributions across all categories to get the total χ² statistic for goodness-of-fit or independence tests.

Observed Frequency

Expected Frequency

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Statistics

Confidence Interval Calculator

Compute the margin of error around a sample mean for a 90%, 95%, or 99% confidence interval using the z-distribution. The half-width of the CI tells you how precisely your sample estimates the population mean — essential for survey reporting, scientific publication, and any inference.

Sample Size (n)

Standard Deviation

Confidence Level

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Key differences

	Chi-Square Test Calculator	Confidence Interval Calculator
Category	Statistics	Statistics
Inputs required	2	3
Result	Chi-Square Value	Margin of Error (±)
What it does	Compute the chi-square test statistic contribution for one observed-vs-expected category pair using χ² = (observed − expected)² / expected. Sum these contributions across all categories to get the total χ² statistic for goodness-of-fit or independence tests.	Compute the margin of error around a sample mean for a 90%, 95%, or 99% confidence interval using the z-distribution. The half-width of the CI tells you how precisely your sample estimates the population mean — essential for survey reporting, scientific publication, and any inference.