The STDEV function is a built-in function in Microsoft Excel (and in other spreadsheet programs) that calculates the standard deviation of a range of values. The standard deviation is a measure of how spread out the values in a data set are from the mean (average).
The syntax for the STDEV function is as follows:
=STDEV(value1, [value2], …)
where value1, value2, etc. are the cells or ranges of cells that contain the data set.