The perfect dimension for your photo collage is 1080×1080 pixels.
This will work on any social media sites if you wish to post it and also is a good choice for
print.
With PixTeller editor you can make photo collage posters (800×1200 pixels)
or photo collage card (1200×630 pixels).
Also if you want a custom dimension for your photo collage, you may select any preset size or
enter the desired values into the width and height page properties inputs, from the collage
editor.