Where do the column headings begin and end in Excel?
Column headings start at A. After reaching Z, the next is AA,
then AB and so on. What the last column is will depend on the
version of Excel that you have. Column IV, which is the 256th
column, is in the versions up to Excel 2003. From Excel 2007 there
are 16,384 columns and last one is column XFD.