T.TEST function

Returns the probability associated with a Student's t-Test. Use T.TEST to determine whether two samples are likely to have come from the same two underlying populations that have the same mean.



The T.TEST function syntax has the following arguments (argument: A value that provides information to an action, an event, a method, a property, a function, or a procedure.):

  • Array1     Required. The first data set.
  • Array2     Required. The second data set.
  • Tails     Required. Specifies the number of distribution tails. If tails = 1, T.TEST uses the one-tailed distribution. If tails = 2, T.TEST uses the two-tailed distribution.
  • Type     Required. The kind of t-Test to perform.


If type equals This test is performed
1 Paired
2 Two-sample equal variance (homoscedastic)
3 Two-sample unequal variance (heteroscedastic)


  • If array1 and array2 have a different number of data points, and type = 1 (paired), T.TEST returns the #N/A error value.
  • The tails and type arguments are truncated to integers.
  • If tails or type is nonnumeric, T.TEST returns the #VALUE! error value.
  • If tails is any value other than 1 or 2, T.TEST returns the #NUM! error value.
  • T.TEST uses the data in array1 and array2 to compute a non-negative t-statistic. If tails=1, T.TEST returns the probability of a higher value of the t-statistic under the assumption that array1 and array2 are samples from populations with the same mean. The value returned by T.TEST when tails=2 is double that returned when tails=1 and corresponds to the probability of a higher absolute value of the t-statistic under the “same population means” assumption.


The workbook below shows examples of this function. Inspect them, change existing formulas, or enter your own formulas to learn how the function works.

To work more in-depth with the example data in Excel, download the embedded workbook to your computer, and then open it in Excel.

Applies to:
Excel 2013, Excel Online