The original slide size in Microsoft PowerPoint corresponded to projector and monitor dimensions, a scale of 3:4. This was based on the dimensions of television. However, the majority of monitors and projectors now use dimensions of 16:9. Both PowerPoint and Apple KeyNote offer 3:4 and 16:9 as standard choices.
Slightly more challenging to find is the ability to format slides as 1:1, better known as square. For social media purposes this is convenient since the default image type for Instagram is square. Several companies that publish photo books also have square-image formats.
KeyNote and PowerPoint provide the option to format slides as square. This post demonstrates the process for KeyNote.
To change the slide dimensions, click on the ellipses (…) and select Document Setup. Click on Slide Size and select Square.
It is helpful to do this before you create a slide deck. Otherwise you will have to reformat content.
Export Slides As Images
After completing your slide deck you will want to download the slides as images. As before, click on the ellipses (…) and select Export. Choose Images. Select the desired slides to export, pick a format and click Export. You will see a prompt on where to send your images. I usually choose to download to the camera roll.