I had extracted data for a client from their Great Plains financial system quite a few years back and the report was saved in the older excel format that uses the. .xls extension. The file size was 300 MB because I used Macro/VBA to pull more than 3million rows from the system. Recently, my client called me to upgrade the report. I save the file in the newer .xlsm format. I know the file size is likely to drop with the new format but was surprised to see that it dropped from 300MB to almost 30MB. That’s a 90% savings in space. Well done, Microsoft for developing the new format.