Create a Quad Split Screen in Premiere Pro with these Position and Scale values
Here's a nifty reference for resizing 1080 HD footage into a 1080 HD quad split screen. Read more for the download link.
Here are the values:
Scale all 1080 HD clips to 50.
Top Right: 480 | 270
Bottom Right: 480 | 810
Top Left: 1440 | 270
Bottom Left: 1440 | 810
There is an endless variety of templates and effects that will produce more stylized results. This is only for creating a basic quad spilt screen in Premiere Pro. The screen grab of the motion settings in each window corresponds to that particular window. This will help you memorize the values needed to produce a symmetrical quad split screen that fills the entire canvas.