Quickly change your slide size in Microsoft PowerPoint. First, go into the Design tab and select Slide Size from the right side. Then, you can choose between 4:3 (4 x 3) or 16:9 (16 x 9). You can also choose a custom slide size and input any size you would like to present. And that's it! This method for changing slide size works for Microsoft PowerPoint 365, 2021, 2019, 2016 and 2013.