The CONFIDENCE.T function returns the confidence interval for a population mean, using a student’s t distribution.

**Syntax**:= CONFIDENCE.T(alpha,standard_dev,size)

The CONFIDENCE.T function syntax has the following arguments:

**Alpha**Required. The significance level used to compute the confidence level. The confidence level equals 100*(1 – alpha)%, or in other words, an alpha of 0.05 indicates a 95 percent confidence level.**Standard_dev**Required. The population standard deviation for the data range and is assumed to be known.-
**Size**Required. The sample size.

**Example**: Let’s look at some Excel CONFIDENCE.T function examples and explore how to use the CONFIDENCE.T function as a worksheet function in Microsoft Excel:

In the spreadsheet below, the Excel Confidence.Norm Function is used to calculate the confidence interval, with a significance of 0.05 (i.e. a confidence level of 95%), for the mean of a sample of heights of 200 men. The sample mean is 1.75 meters and the standard deviation is 0.08 meters.

**Syntax**: =CONFIDENCE.T(B1,B2,B3)

**Result**: 0.011155071

The above function returns a confidence value of 0.011155071

Therefore the confidence interval is 1.75 *± 0*.011155071, which is equal to:

1.738844929 to 1.761155071

**Note**:

- if any argument is non-numeric,
**CONFIDENCE.T**returns the*#VALUE!*error value - if
**alpha**is ≤ 0 or ≥ 1,**CONFIDENCE.T**returns the*#NUM!*error value - if
**standard_dev**≤ 0,**CONFIDENCE.T**returns the*#NUM!*error value - if
**size**is not an integer, it is truncated - if
**size**< 1,**CONFIDENCE.T**returns the*#DIV/0!*error value