Excel file sizes

[pulpwood007]

I have recently switched to Office 2010 and am converting my old .xls files to .xlsm files. Since I use macros in some of my spreadsheets this seems like a reasonable choice. Any reason to use the .xlsx files? Even for those that don't use macros?

Also, why is the size of the of the .xlsm file about half of the old. xls file?

thanks,

 

[Irene]

Possibly some interesting comments here:
XLSB vs XLSX and XLSM | Windows Secrets Lounge