t Calculator: Critical Value and P-value Calculator

Step 1: Pick an input mode

Enter t statistic directly — useful when you already have t and df from software
One-sample — paste raw data and a hypothesised mean μ₀. Outputs a CI for the sample mean.
Paired — two columns of equal length (before / after). Outputs a CI for the mean difference.
Two-sample (Welch's) — two columns of any length. Outputs a CI for the difference in means.

Significance level (α): Common values: 0.05 (5%), 0.01 (1%), or 0.10 (10%). Used for critical values and the (1−α) CI.

Degrees of Freedom (df): Must be a positive integer

t test statistic: Your computed t value

Hypothesised mean μ₀:

Raw data (one column): Comma, space or newline separated. Non-numeric tokens are ignored.

Raw data (before / group A):

Raw data (after / group B — same length, same order as above):

Group A data:

Group B data:

Test Results

Test Type	P-value	Critical Value
Left-tailed test	-	-
Right-tailed test	-	-
Two-tailed test	-	-

Statistical Summary

Significance Level (α): -

Degrees of Freedom: -

Test Statistic: -

Enter values and click Calculate to see results.