Paired t test calculator
Paste before and after measurements in matching row order. The calculator tests the mean paired difference against zero.
Pairs and differences
| Pair | Before | After | Difference |
|---|---|---|---|
| Fill in the fields above — the result is computed on this page. | |||
How do I use this page?
- Paste both measurements in matching order.
- Check the mean and SD of the differences.
- Read t, df and the two-sided p value.
What this page does not do: The test assumes independent pairs and an approximately normal distribution of differences. Very small samples or strong outliers can make the result misleading.
Further reading
Theory — what is the paired t test?
The paired t test compares two measurements taken on the same units, for example before and after a change. The calculation works on the paired differences, so the row order of the entered data matters and must be kept consistent in both columns. A small p-value shows that such a large mean paired difference would rarely occur by chance if there were truly no difference. Every value in the first field must have a matching value in the second, since this is not a test for two independent groups.
Frequently asked questions
Is this for two independent groups?
What does a negative mean difference mean?
See also
A/B test calculator
Compare two proportions in an A/B test. Calculate conversion rates, difference, uplift, z score, p value and c
A/B test planning — sample size, MDE and duration
Plan a two-proportion experiment, estimate detectable effect and traffic duration.
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.