Saving to .xls increase the file size by 5x

[Saqib Ali]

Has anyone noticed that if you open a Excel 2003 .xls file using
Excel 2007 and then save it back to .xls (2003 compatibility mode),
the file size increases by 5x? 1 MB .xls file becomes 5+MB .xls
file......

However saving the file to .xlsx reduces the file size?

What gives?

Note: This doesn't happen with all xls file. It only happens when were
are using certain functions / features. However I haven't figured out
what causes it........


saqib
http://doctrina.wordpress.com/

 

[Jim Rech]

Typically I see a small increase in size, like a few K. Part of that is due
to the 40 or so new named Styles that are introduced automatically. "20% -
Accent1", "Accent1", "Bad", etc. I wouldn't think that was necessary.

--
Jim
| Has anyone noticed that if you open a Excel 2003 .xls file using
| Excel 2007 and then save it back to .xls (2003 compatibility mode),
| the file size increases by 5x? 1 MB .xls file becomes 5+MB .xls
| file......
|
| However saving the file to .xlsx reduces the file size?
|
| What gives?
|
| Note: This doesn't happen with all xls file. It only happens when were
| are using certain functions / features. However I haven't figured out
| what causes it........
|
|
| saqib
| http://doctrina.wordpress.com/

 

[Saqib Ali]

Typically I see a small increase in size, like a few K.  Part of that is due
to the 40 or so new named Styles that are introduced automatically. "20% -
Accent1", "Accent1", "Bad", etc.  I wouldn't think that was necessary.

It appears that Excel 2007 adds something called themeManager.xml that
that bloats the file when you save it in the compatibility mode
(i.e. .xls).

I am not sure what themeManager.xml does?

saqib
http://doctrina.wordpress.com/

 

[Saqib Ali]

I tried dissecting the .xls (2003 compatibility mode) file, and it
appears that Excel 2007 adds a reference to something called
themeManager.xml when you save the files in the 2003 compatibility
mode (i.e. .xls). I couldn't find any useful information about
themeManager on Microsoft's website, but from what I understand, it
defines the formatting of a document. This additional xml metadata
causes the the file to bloat. And since native 2007 (.xlsx) is a
zipped file format the file size increase is not noticeable, but when
saving to .xls format (non-zipped) the file size increase is
striking.

I posted this question on GetSatisfaction.com and Kathy Jacobs
responded as follows:

---------------------------------------------
It will happen with most files. The new file type is a much more
compact set of files that are then zipped together. When you back
save, the graphics and features for both versions are put together in
the old format.

One way to think about it is to think back to the changes when Office
97 came out. The compression rate for the new file type is another
level better - but for the old programs to read it, both sets of
information have to be there.
-------------------------------------------
(see: http://getsatisfaction.com/microsof...s_in_excel_2007_increases_the_file_size_by_5x)


So the only solution is is to remove all formatting and theme before
saving the to .xls file format (compatibility mode) using Office 2007