T test calculator
Choose a one-sample test, pooled two-sample test, or Welch unequal-variance test.
How do I use this page?
- Choose the test variant.
- Paste one or two samples.
- Read t, df and p.
What this page does not do: The test requires independent observations within groups and a sufficiently regular sampling distribution of the mean.
Further reading
Theory — what is a t test and when to use it?
A t test is a statistical method that checks whether a mean or a difference between means is significant relative to its standard error. The calculator supports three variants: a one-sample test, a pooled two-sample test for equal variances, and the Welch test for groups with unequal variances. Welch's version does not require equal variances, so it is usually the safer default when comparing two independent samples. The right choice depends on how the data and number of groups are structured.
Frequently asked questions
Welch or pooled variance?
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.