The first step in using a custom background in Microsoft PowerPoint is to obtain or create a compatible file type in the proper dimensions for your display hardware.

Many online sources offer pre-sized, royalty-free backgrounds in every subject imaginable. For presenters familiar with painting and photo software like Adobe PhotoShop, creating an original background may be an option worth exploring.

For use on a standard American computer screen, video monitor or projected screen, your file should be in a 4:3 ratio. That means four parts horizontal to three parts vertical. The area in pixels may vary but the proportion will remain the same. 800 x 600 and 1024 x 768 are the two most common sizes. Either size will stretch perfectly out to every corner of your slide.

The default setting in PowerPoint for a "Blank Presentation" as "On-screen Show" display will have the 4:3 ratio. PowerPoint deals in inches rather than pixels however, and the 4:3 ratio will display as a 10" by 7.5" horizontal (landscape) format.

Creating a widescreen 16:9 ratio background is a simple matter of having wider artwork and adjusting PowerPoint dimensions in Page Setup. The canvas size for your artwork should be 1024x576 and your PowerPoint dimensions should be 14.22 x 8.00 inches.

JPEG (.jpg) files with a maximum quality setting are highly recommended as the file type of choice. Photographic detail is good and the file sizes are typically much smaller than other methods of file saving. In a large presentation that can make a huge difference, especially if you will need to send your file to others via e-mail.

Another way to keep your file size down when using older versions of PowerPoint is to use the background common to the largest number of your slides, in your Slide Master. If your presentation is twenty slides long and fifteen of them are bullet-point slides, then the background created for bullets should be in your Master. The remaining slides would each have their own custom background applied at the Slide level. In newer versions of PowerPoint, multiple Slide Masters are supported, rendering the decision moot.

Once you have a background file selected, and the PowerPoint file is sized properly using Page Setup, you