How to reduce presentations in filesize

Obvious answer would be: LESS SLIDES !  I agree, of course, but that would not make for a useful blog post.  Imagine you did a really good job in using few slides, reduced the amount of text on your slides, and used a lot of images to create a good visual audience experience.  You might end up with a short presentation that is short but large in size, Mb wise.  Too large to share or too email?  Let me share a few techniques on how to reduce presentations in filesize.

Why presentations are too large in size is easy to explain: they are so large because that is how we make them.   We use too many slides, use elaborate templates, include videos and use images that are too large and only realize that our presentations have become huge once they are done.  Compressing the presentations afterwards does typically not reduce the size a lot.  So what other options are there?

This post is a result of me receiving a presentation of only 39 slides that was 43.9Mb in size.  After some research, here are the 3 things I did to reduce the size dramatically, without having to give into quality, before sharing it myself with my colleagues.

Disregard size initially

The good thing about the 3 tricks below is that they can be applied when you are completely done with your presentations.  So whilst creating your presentation, go crazy and disregard file size completely.  Actually, only apply them just before you want to share or email your presentations, and preferably on a copy of the original.

Reduce images in size

We tend to use a lot of images in our presentations.  And we select them from wherever we can find them.  We most often disregard how large in size the images are or use huge images and then scale them back in size on our slides as we only need to show a much smaller version of the original.  There is a trick to scale down the filesize of the image and adapt it to how you use it in your presentation.

1. Click on any image on any slide
2. Choose ‘Format’ from the top menu.
3. Choose ‘Compress Images’
4. Untick the ‘Apply only to this picture’ to compress all images on all slides in 1 action

5. Click ‘OK’

This does not seem to apply to images being used in template master slides.  I started no longer adding images on master slides, or only use images that were sized down already.

My presentation went from 43.9Mb to 34.2Mb in size this way.

Hunt for other large elements

The latest versions of PowerPoint saves in an xml format.  This is something for us to exploit as it allows us to analyze the content of this ‘xml’ file in different ways:

1. Save and Close the presentation
2. Rename your presentation by changing the file extension from .pptx to .zip
3. Open the new zipfile using a zip program as if it were a zip file.
4. open into the ‘ppt’ folder
5. open the ‘media’ folder

It turned out the presentation included a video of 18Mb that I could not reduce but explained why the presentation was so big, but also an image that was 9Mb in size, although it was visualized on a slide no bigger than the size of my thumb!

6. once you found a large media file, just open the file to get to know the content of the file.
7. Do not forget to rename the presentation extension back to .pptx

So my presentation went from 34.2 Mb to 25.1 Mb.

I could have reduced the presentation further, down to 7Mb or so, by replacing the video with a link to the video somewhere in he cloud, but I chose not to.

Remove unused master slides from the template

As a last step, with some surprising results, you can reduce the size of a presentation by removing unused template master slides from a presentation.  You can do this manually, but that is tedious, or create a little macro that you need to run once.  Here is what i did to do so:

1. From the top menu, choose ‘View’
2. choose ‘Macros’
3. In Macro name press any letter, then the Create button
4. Copy and paste the code below to replace everything in the window that appears. this script will basically loop through all master slides and remove those that are not being used in your presentation.

Sub SlideMasterCleanup()

Dim i As Integer

Dim j As Integer

Dim oPres As Presentation

Set oPres = ActivePresentation

On Error Resume Next

With oPres

For i = 1 To .Designs.Count

For j = .Designs(i).SlideMaster.CustomLayouts.Count To 1 Step -1

.Designs(i).SlideMaster.CustomLayouts(j).Delete

Next

Next i

End With

End Sub

5. Press F5, or green run arrow at the top

And this took my presentation from 25.1 Mb to 22.7 Mb.

Conclusion

Presentation do not have to be as big at they typically are!  Presentations can be reduced in size without having to compromize on presentation quality.

Ignoring the embedded video I saved 81% in the presentation file size by applying the 3 steps above.

But don’t forget that just using less slides is not a bad idea either 😉