PST file compression ratio

[SJMP]

Does anyone know how much a pst compresses data when exporting a exchange
mailbox to .pst file?

Or a tool which would tell you the size of a .pst file if not compressed/ or
exported to an exchange mailbox?

Thanks
SJMP

 

[Roady [MVP]]

That completely depends on the contents on the mailbox and moreover; the
file formats of the attachments.

On average an ost-file is about 25-30% larger than the size of the reported
size of the server mailbox in Outlook. As ost-files and pst-files compare
pretty much 1:1, that is what you can expect in size.

Note that importing pst-files back into Exchange will never give you back
the efficiency of Exchange as single instance storage will no longer apply.