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Saqib Ali
sad I’m frustrated

Saving to .xls in Excel 2007 increases the file size by 5x

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........
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  • Kathy Jacobs
    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.
    • Kathy,

      thanks for the response. That was very helpful.


      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.


      So I guess the only solution is is to remove all formatting and theme before saving the to .xls file format (compatibility mode) using Office 2007
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  • Ananda Sim
    Hmm. Thanks for the heads-up Saqib. Themes are an extension to Office "classic" - in Office 2007, the thrust is to allow a "consistent look" to all of Word, Excel, Powerpoint. They also had to support the classic features and data. So, they extended Office by creating themes - which is not easy - because Word, Excel and Powerpoint's roots are from those days when they were standalone programs, not designed to work as one. Obviously theme data must be stored somewhere.

    I was testing Word document save as "classic" .doc vs docx. Docx appeared to be a smaller file as well. These xml format files are zipped - that explains why the actual file is small even though the original naked xml file may be bigger. The "classic" Office document datafiles were optimised for fast loading, not smallest size.

    I've just started an Office 2007 blog - feel free to visit.
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  • Peter K
    sad I’m frustrated
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    So basically Microsoft does NOT support saving files back to true .doc or .xls format. Instead they insist on including XML garbage, which makes the files N times bigger and performance N times slower. Thus forcing us to upgrade to Office2007. And we are supposed to see this as a benefit, uhhh how exactly again???
    • The benefit is not to making your old .doc and your .xls even better. I bet MS didn't even put that on their agenda. The benefit is that the new .xlsx and .docx have more features. Think of it this way. You buy a new large wide, flatpanel TV. It won't fit on your dinky classic TV table. That's not the point - you need to get a new TV table.

      Excel 2007 is a strong product. It uses all the CPUs in your dual core or quad core system (AFAIK). It supports heaps more rows and columns. It calculates faster. The table formatting also sneaks in table control of regions so that newbie users don't break their data by sorting one column without carrying the other columns.
    • Ananda,
      Good analogy. But overlooking one key thing - you don't share you TV with your neighbors and friends. On the other hand you have to send the Word documents and Excel sheets to you business partner, who may or may not have Office 2007. So you need to save it to a lower version for compatibility reasons.
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  • Ananda Sim
    happy
    I haven't tried it Saqib, but how about having a blank .xls file (could could a template) from Office 2003. Work with it in Office 2007 but stay away from the funky table formatting or any theme based formatting. Be careful to only use classic commands. Then save it and compare.
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  • Ananda Sim
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    Ok, so we have identified the cause of the bloat. Excel 2007 is adding metadata and data from the enhanced formatting functions and this data is probably XML not binary (which the original Excel BIFF format was).

    Simply, someone or Microsoft could develop a more efficient stripper for the down-rev files - Word files saved as HTML are pretty much yecch! because there are all kinds of mso formatting and metadata - eventually after several years, Microsoft designed a HTML save that stripped nearly everything and so did third parties.

    Maybe the Excel MVPs
    http://www.exceluser.com/explore/link...

    will have something cooking. You could ask whether anyone has a project going:

    http://groups.google.com/group/micros...
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  • RSageTX1
    What about exporting to Excel from another product such as SSRS 2005 Bld vs 3239? Our customers have complained that the file export to excel is large but if they open it and save it to even the same file name it will drop in size. They don't like having to do that for each of their reports.
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  • nick chong
    sad
    I just used a 3rd party product from topshareware.com to do a conversion of xlsx format and the result was same as using MS Excel to do the conversion....seems like the only resolution is using another software in coexistence to replace MS Excel 2007 specifically for xls handling (can't use Excel 2003 right??)
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  • woodymax
    I am aware that this posted thread has been around for over a year, but I wanted to share some additional information I found on the subject.

    Info Regarding File Extension Xlsx

    Microsoft has stated several benefits to using the new .xlsx format including reduced file size, increased security, improved interoperability between Office products, and better file recovery technology. In terms of the file size issue, it is reported that the new .xlsx file can be up to 75% smaller than previous .xls files. Excel automatically compresses the .xlsx file (using ZIP compression) when the file is saved, and uncompresses it when it is re-opened. The compression allows for easier and quicker transfer of files between computers or over a network.

    The .xlsx format is essentially a container but Microsoft has introduced new terminology to reflect its new open formats. Instead of calling their structure a container, they have chosen the word “package”. Inside the package are three groups of “parts”. The first group contains three individual parts that store information about document properties, application properties, and customized document properties. The second group contains the data for the individual worksheets, while the third group stores information about styles, charts, and strings. The third group of parts is stored relationally to each individual worksheet.

    I hope this helps to clarify the reason for the compression of .xlsx formatted files.

    Woodymax

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  • Simon
    sad I’m Frustrated
    SO is their any way to bulk save documents in the new xlsx format from xls using office 2007?

    I have thousand of older docs and when people save int he new format, they end up with duplicate docs...one xls and one xlsx.
    • There is no reason on my part to convert thousands of old documents to .xlsx.

      You make new .xlsx when you need to and if your old document needs a new Excel feature, then save it as .xlsx, remembering to delete the old .xls file, one file at a time when you use the file.

      If you don't use the old files, leave them alone. If you use the old files but just edit a cell or two, I don't see any reason to purposely save them as .xlsx.

      If you want for some reason to convert all your thousand .xls files to new .xlsx files, then a VBA macro that enumerates and iterates through all the files can do the job for you.
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