Hi,

When trying to compress a very large Excel file (30MB) either with Winzip
or WinRar, the compression does not result in a significant reduction (max.
-3% only in the best compression mode).

From my experience it seems to me that there is something like a
'hidden/magic' limit around ~25 MB and below this a compression is not a
problem, but above it is. Even if the large file is reduced back to a very
small one, the compression still does not result anymore in a significant
reduction (e.g. when deleting data in the 30MB file to bring it back to 5MB,
the following compression result is still max. -3%).

The size of the 30 MB is mainly driven by: ~2500 data sets as rows with 50
basis data information columns plus further 150 complex calculation columns
including lookup references to around ~30 parameter tables on another sheet.
Additionally, around 30 referenced charts are part of the file plus 1 pivot
overview table for the result.

The most commonly heard resolution approach is to do it at least in Access
and not in Excel due the data amount and required
calculation/parameterization effort. BUT there is a business reason behind
why it is done this way. Hence, does anybody has a good idea how to get the
file compressed to a size ~ 5MB (that's what I reach if the basis file is
<25MB)?

I have also heard that this issue is maybe related to an 'Excel internal
compression algorithm'. Does anybody know something about this?

I really appreciate your feedback/support and would like to thank you for
your help in advance,
Thorsten