It is best to know your output display device upfront. You better start a presentation in a given resolution or size, before you add shapes and images to slides. Changing the dimensions afterwards is possible, but it can ruin your slide design.
You can run your slideshow on a computer screen, a television screen or projector. It is not that important to know what type of device you will be using, but you must know the output display resolution. A common output size for this is 1920 by 1080 pixels.
Presentation dimension vs screen resolution
By default, the size of the new presentation in PowerPoint, is currently a widescreen type presentation, 13.333 inch by 7.5 inch. Mostly you will have 96 dots per inch (dpi) on your screen settings, so this means that a default PowerPoint presentation has a resolution of 1280 by 720 pixels.
A common term that you hear for televisions and videos is HD quality, or High Definition quality. This is an agreement in the industry that 1920 pixels by 1080 pixels is HD. So when you have a video in HD quality, then the size of your video is 1920 x 1080. When your television is a HD television, then it can playback HD video or HD television channels in that same dimension of 1920 x 1080 pixels.
Default PowerPoint is NOT HD
So we know that the default dimension of a presentation is 1280 x 720, and that your HD television is capable of displaying 1920 x 1080. You see already a problem with default PowerPoint presentations. Default PowerPoint presentations are not in HD; they are of lower quality. And this is not ideal when using PowerPoint for digital signage.
Is that a problem? Not necessarily. When you run a smaller PowerPoint slideshow on a larger television or computer screen, then PowerPoint will always enlarge the presentation so that it will fit on your screen. The other way around is also true. PowerPoint will reduce the output size when the presentation design is larger than the output size.
Imagine you have a textbox on a slide with text in black, on a white background and a rectangle around it. The presentation setup is 50% of your final output dimensions. So PowerPoint will double each size automatically. So your textbox of maybe 500 by 150 pixels, will be converted into a textbox of 1000 by 300 pixels. And your border of 10 pixels, will be displayed as a border of 20 pixels now. This will work. You will see that it is bigger, but the relation between height and width is respected, and basically, nothing is wrong. A black pixel of your text, will result in a double black pixel now. No problem here at all. The only problem that might arise, is mistakes or unexpected results by roundings.
The problem will occur when you are using other types of shapes like images and videos on your slide now. A picture is more complex than just a regular black and white rectangle with text. The colors of the pixels on a picture are so much more complex and diverse. When a picture is enlarged, a computer program has to ‘invent’ pixels. Basically it will double pixels, but it is more complex, even when multiplying and rounding pixels. So your nice picture might not be that nice when enlarged.
For the resizing of the pictures and videos you have to be careful. When you have pictures and videos on your slides, or when you want to have high quality output where every pixel is worth the effort, then it is needed that you set the slide dimension correct for the highest quality.
Setting pixels in PowerPoint
At the start, I explained that currently a default PowerPoint presentation starts with 13.333 inch by 7.5 inch. In PowerPoint 2013, click Design in the normal PowerPoint menu, and then click the Slide Size button.
- Standard (4:3)
- Widescreen (16:9)
- Custom Slide Size
For the Custom Slide Size you need to click that 3rd option and you will see this options form: