Statistical

Z.TEST Function in Excel

Returns the one-tailed p-value of a z-test.

Syntax

  • =Z.TEST(array, x, [sigma])

Arguments

  • array (required): Data to test
  • x (required): Value to test
  • sigma (optional): Population standard deviation

Examples

  • =Z.TEST(A1:A20, 4) - Z-test p-value - Result: p-value

Z.TEST for data analysis

  • Confirm whether you need entire columns, filtered subsets, or distinct values.
  • Use [COUNTIFS](/functions/countifs/) and [SUMIFS](/functions/sumifs/) for multi-criteria metrics.
  • Pivot tables complement single-cell statistical formulas for exploration.

Common errors

  • Uses sample std dev if sigma omitted

Use cases

  • Hypothesis testing
  • Mean testing
  • Quality control

Frequently asked questions

  • What is Z.TEST used for? Z.TEST performs a z-test and returns the one-tailed p-value, testing whether a sample mean differs significantly from a hypothesized value. Use it when you know the population standard deviation or have large samples (n>30).
  • When should I use Z.TEST vs T.TEST? Use Z.TEST when: population standard deviation is known, or sample size is large (n>30). Use T.TEST when: comparing two samples, population stdev is unknown, or sample is small. Z.TEST tests one sample against a hypothesized value.
  • How do I get a two-tailed p-value from Z.TEST? Z.TEST returns one-tailed p-value. For two-tailed: =2*MIN(Z.TEST(array, x), 1-Z.TEST(array, x)). Or simply =2*Z.TEST(array, x) if testing whether sample mean is greater than x. Multiply by 2 to account for both tails.

Editorial review

  • Reviewed by Excel.Directory Editorial Team. Updated May 2026.