The COUNTBLANK function is a statistical function which counts only the cells within the selected range which are empty and do not contain any value. This will not count formulas which evaluate as blanks.

This is the format of the COUNTBLANK function:

=COUNTBLANK(Range 1, Range 2, Range 3, etc…)

Here is an example of the COUNTBLANK function:

=COUNTBLANK($A$1:$A$6) = 6 (when in an empty worksheet)

It is very useful when you require a count of invalid responses to a form or survey, or to provide context to an analysis being done where you can attribute blank cells to a valuable output.

An example of a functional implementation would be calculating the number of missed shifts an employee had has in a given period, or how many vacation days they have left in their bank. You would use a COUNTBLANK function for this as you can isolate only the cells which do not contain values. Assuming you track days off by leaving cells blank, and each employee is granted two days off per week, you could track additional days off of work by finding the blank cells in a week or month of your scheduling workbook.

=COUNTBLANK($C3:$I3)-2 = 2-2 = 0

Which would be the result of scanning the week of work hours for the number of empty (not scheduled) days, and removing the two mandatory weekly days.