## How to use the CONFIDENCE function

*Article updated on March 29, 2018*

The CONFIDENCE function calculates the confidence interval for a population mean, using a normal distribution.

Formula in cell B6:

### Excel Function Syntax

CONFIDENCE(*alpha*, *standard_dev*, *size*)

### Arguments

alpha |
Required. The significance level used to calculate the confidence level. 0.05 represents a 95% confidence level. |

standard_dev |
Required. The standard deviation for the data points. |

size |
Required. The number of data points. |

### Comments

The CONFIDENCE function returns an #VALUE! error if an argument is not a number.

The CONFIDENCE function returns an #NUM! if alpha is less than 0 (zero) or more than 1.

### Functions in 'Compatibility'

The CONFIDENCE function is one of many functions in the 'Compatibility' category.