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How to find the cause of large Powerpoint files?

Have you ever been sent a PowerPoint presentation file and wondered why it filled your mailbox? Or have you ever sent a PowerPoint presentation by email and received complaints about the size? Or have you ever created a PowerPoint presentation and thought twice about sending it by email because it is so large? If so this article is for you and it can be quite simple to find the answers.

There's no easy way within any version of PowerPoint to find why a presentation is so large. There are numerous articles on the web with good ideas about how to decrease the file size but they may not help much unless you're focusing on the biggest items.

The secret to finding out which are the biggest items in a PowerPoint is to know the format of a PowerPoint pptx file. This type is used by default by Office 2007 and later but can be saved by Office 2000, Office XP, or Office 2003 when a compatibility pack is installed. A pptx file and docx and xlsx and the other Office 2007 types are zip files.

An Office Open XML file is a ZIP-compatible OPC package containing XML documents and other resources. That is, one can see the contents of an OOXML file, for example by renaming it to a .zip file and opening it with any zip tool. The actual .xml files can then be viewed in a web browser or a plain text editor.

So, the easy way to look at a PowerPoint and its components is to save a copy, rename it to a zip and open it. I recommend not using Microsoft Windows Compressed Folders as you can't list all the contents easily.

Here's an example of a large pptx that I renamed to a zip and opened using UltimateZip (there are plenty of other tools,  including WinZip or PKzip or even Windows Explorer). I have cropped the screenshot but I think you can see the most offending item:

example of a pptx opened as a zip
And with a zip file tool, I can double click on the offending item and open it - in this case it is an image and I can see which it is.

So now you know what items are bloating your PowerPoints and can follow other web advise to downsize them if necessary.

Comments (2)


Many thanks all!

Nice piece of information.


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