Author: Oscar Cronquist Article last updated on October 01, 2018

The CONFIDENCE.NORM function calculates the confidence interval for a population mean.

Formula in cell C7:


Excel Function Syntax



alpha Required. The significance level.
standard_dev Required. The standard deviation.
size Required. The number of samples.


The CONFIDENCE.NORM function returns:

  • #VALUE! error value if any argument is non-numeric.
  • #NUM! error value if
    • alpha <= 0 (zero) or alpha >= 1.
    • standard_dev <= 0.
    • size < 1.

CONFIDENCE.NORM function truncates size numbers to integers.