Help! Why Is My PowerPoint File So Big?

One of the many questions that we receive at the Bluewave studio is, “Why are my PowerPoint files so huge (in terms of file size)?”

Well, a picture is worth a thousand words—and also a thousand kilobytes.

When you add photos to a presentation, obviously the PowerPoint file size is going to get bigger. Even just one high resolution image can increase the file size dramatically. Add a few more and you may experience problems with slow-running apps, projection, downloading, and storage. And of course it can be difficult to email those big files to a client or a co-worker.

Cropping or scaling might seem to be a way to address the problem. The image is reduced—doesn’t that affect file size? Unfortunately, no or not by much. The inherent size information of the original image is still held within the file.

large image on PowerPoint slide
cropping an image using PowerPoint

Sometimes maximum image quality is the goal, especially for high-end events where big file sizes are not a deal-breaker. But if that’s not the case for you—if a smaller file size is critical—here are a couple of things you can do.

Solution 1: Image Compression

Image compression reduces the image pixels per inch (ppi), which in turn reduces the presentation file size. Reducing ppi can affect image quality and appearance, but you will be able to test the results and try other ppi settings before saving and closing the file.
There are several ways to achieve image compression in PowerPoint.

  1. Set image compression for the entire presentation. On the File menu, select Options > Advanced. Under Image Size and Quality, deselect “Do not compress images in file,” then choose one of the three target output ppi settings:PowerPoint image compression popup

Print (220 ppi): excellent quality on most printers and screens
(this is PowerPoint’s default ppi setting)

Screen (150 ppi): good for Web pages and projectors

E-mail (96 ppi): minimize document size for sharing

You may not be able to tell much difference between 220 ppi and 150 ppi (it all depends on the original image), but 96 ppi may result in a noticeably lower image quality. Experiment to see what is an acceptable trade-off in file size vs. appearance. If your images already are low ppi, then image quality and file size will probably not change.

Note: These settings will only affect the current presentation.

  1. Set image compression for individual pictures. Select a slide image. On Picture Tools under the Format tab, select Compress Pictures.PowerPoint picture compression options

You can apply ppi changes to the selected picture or to all pictures in your presentation. If you’ve cropped an image, selecting “Delete cropped areas of pictures” will also help to reduce file size.

The effect of the target output ppi settings is the same as described in #1 above, so make sure the change in image quality is acceptable. To undo (before saving and closing the file), go through the same steps to return to the original ppi setting or try another setting.

Note: “Use document resolution” means Powerpoint’s default 220 ppi will be in effect, unless you changed to a lower overall presentation image setting.

Solution 2: Optimize the Photo with Photo-editing Software

Far too often, images placed in PowerPoint are overly large in dimension with a far higher than necessary ppi resolution. It happens—we see this all the time with presentations sent to us by clients who aren’t familiar with the issues related to using photography in their files.
Here’s an example:
large image inserted in PowerPoint can make PowerPoint file size too large

It looks great in screen show mode, but the file size for that one slide alone is 32MB! What’s going on?
Bluewave’s first step is to make the original photo more manageable from the get-go, using a photo-editing program such as Adobe Photoshop. When we opened that image in Photoshop, here’s what we found:

large image settings in PhotoShop
Original image settings
resized image settings in PhotoShop
Resized settings

Under Image Size, we discovered the photo is 24” x 24” with a ppi resolution of 300. Way overkill! Too big and too much ppi for use in a presentation.

The fix in this case is simple: we changed the dimensions in Photoshop to 8” x 8” and reduced the ppi to 120 (120 is just used as an example; lower ppi can be fine as well). Replacing the huge image with the new, resized version reduces the file size to 700 KB—big improvement. Taking it further, we then applied PowerPoint image compression settings which further reduced the file size to 207 KB. And if we cropped the photo, image compression settings can delete the cropped areas and reduce the file size even more.

The image still retains the beauty and quality of the original and produces a far more user friendly file size. Sure, it takes a little more work but the end result is worth it.

What if I don’t have an image editing program? Good point! Try this work-around trick with oversized images:

  1. Resize and crop the picture exactly how you want it to appear on the slide
  2. Type Ctrl+C to copy the resized, cropped picture
  3. On the Home tab under Paste, select Paste Special and then click on “Picture (JPEG).” If the image contains transparencies, select “Picture (PNG).”
  4. The pasted picture comes in exactly the size of the resized, cropped picture. The ppi will be the same as that of the original image, but no more than PowerPoint’s default of 220 ppi. You can experiment with lower ppi settings using image compression.
  5. Delete the original picture (you may want to save it elsewhere, just in case)

The result is a great-looking image at exactly the size it is pasted on the slide—and the presentation file size is reduced.

So, the next time you get ready to send your incredible, beautiful deck to your boss, only to realize the file is too large to email–have no fear! Just follow these simple tips to reduce your PowerPoint 2013, PowerPoint 2016, or Office 365 PowerPoint file size and send away!

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