Making PowerPoint files smaller

Trim down those enormous PPT/PPTX files.

While it’s not the problem it was a few years ago, there’s still a need to reduce the file size of a PowerPoint presentation to something more portable for transport or even use on older machines which may have trouble dealing with large file sizes.

Here are some tips for reducing PowerPoint file sizes.

File Format

The Office 2007/2010 PPTX file format gives much smaller files that the earlier PPT format. Simply converting a PPT to PPTX/PPTM will, almost always, reduce the file size.

Remember that the Office Compatibility Pack (for Office 2000/XP/2003 versions of Office) or the free PowerPoint viewer will open or display PPTX files.

Failing that, any PowerPoint 95 format PPT file can be made smaller by File | Save As to the PowerPoint 97 version of PPT. The PowerPoint 97 and later version of PPT automatically compresses image files.

We strongly suggest you compress a COPY of the presentation, leaving the full resolution version available in case you need to revert to it for more editing.


Most of the presentation file size is used up with images or video so that’s what we’ll focus on here. There are other tricks to do with embedding fonts etc but they rarely make enough difference to be worth the trouble.

Many images are imported into Office documents in a higher resolution than is needed for daily use.

Since Office 2002 you’re able to reduce the quality of the images in a PowerPoint presentation. Right-click on any image, choose Format Picture then the ‘Compress’ button on the picture tab. Your quality options are Web/Screen or Print. There is also an option to remove the cropped parts of images. You can then choose to compress only that image or all the pictures in the presentation. This is the same option as in Word.

In PowerPoint 2007/2010 you can compress images automatically from the Tools| Compress Pictures menu in the Save dialog. Look for ‘Automatically perform basic compression on save’.

Insert don’t Embed

It’s tempting to ‘drag and drop’ an image into a presentation but there’s a price for that convenience. Office converts the image to an OLE Object which can be larger than if you choose Insert | Picture to do the same job.

Copy don’t re-insert

PowerPoint is smart enough to know when the same image is used multiple times in a presentation. When that happens a single image is stored in the file and used as required.

If you want to use the same image multiple times, insert the image once then copy it between slides. If you insert the same image multiple times, Powerpoint will probably store multiple copies (ie it’s not smart enough to realize the second imported image is the same as one already in the presentation).


There are third-party tools to reduce PowerPoint file sizes. PPTMinimizer is well regarded and maybe useful if your need is great or you have many files to deal with. There is a free trial version.