COUNTVISIBLE

COUNTVISIBLE()
Returns the number of visible, non blank cells in a range.

REMARKS
* This function excludes hidden cells caused by AutoFilter, Grouping or that have been Manually Hidden.
* You can use the built-in COUNT function to include hidden cells.
* This is similar to the AVERAGEVISIBLE, MAXVISIBLE, MINVISIBLE and SUMVISIBLE functions.
* This page has the equivalent VBA function.