Excel 2003, 2007 and 2010 have a standard column width of 8.43 characters, which is what I’ve been working with for the last 23 years. Here is a good description of how column widths are determined in Excel (for Windows).
In Excel 2008 the default column width of 1.04 inches works out to approximately 10.39 characters in the Windows versions of Excel. Even the tool tip that shows when you use the mouse to adjust column width is different in Excel for Mac — characters per inch is shown first, followed by inches in parenthesis.
And the default column width in the Windows version of Excel is 8.43, which translates to roughly “0.89″ inches in Excel 2008. As you can see the tool tip in Excel for Windows shows 8.43 characters per inch, with pixels in parenthesis.
Set the Standard Width for All Columns in a Spreadsheet
To set the column width for a worksheet in Excel 2010 & 2007 select the menu Home, Cells, Format, Default Width, and then type in a value. In Excel 2003 and Excel 2008 for Mac select menu Format, Column, Standard Width, and then type in a value. Just remember in Excel 2008, that value is inches.