Facebook constantly introduces new ad formats and updates dimensions and specs of existing images and videos. Facebook recommends designing ads while keeping mobiles in mind. To maximize compatibility on both desktop and mobile, it recommends square (1:1) or vertical (4:5, 2:3 and 9:16) aspect ratio. For in-stream videos, it recommends highest resolution available, 16:9 video ratio and file size to be 4 GB max. There are various formats of videos and images that can be used for ads and all of them have their specific size recommendations. Facebook ads manager now allows uploading different images for different formats, like feed image recommended size is 1200 by 628 pixels with width and height to be 476 and 249 pixels respectively.
Disclaimer: The above article has been aggregated by a computer program and summarised by an eCommerce specialist. You can read the original article at Hootsuite