Recommended: Desktop: 180 x 180 pixels – minimum; recommend at least 600 x 600 pixels to ensure image quality
Recommended: Smart phone: 128 x 128 pixels
Recommended: Thumbnail: 32 x 32 pixels
Recommended: Display size desktop: 820 x 312 pixels
Recommended: Display size smartphone: 640 x 360 pixels
Recommended: Minimum size: 400 x 150 pixels
Pro Tip: To avoid any compression or distortion, upload a .JPG or .PNG file (experiment to see which works best) less than 100 KB, and don’t drag to reposition once you’ve uploaded your cover photo.
Recommended: 1200 x 630 pixels
Minimum size: 600 x 315 pixels
Tip: Images with a max width of 470 pixels will show in feed, however, it will appear on page with a max width of 504 pixels
Square photo: 1200 x 1200 pixels
Rectangular photo: 1200 x 630 pixels
Recommended: 1920 x 1080 pixels
Tip: Images narrower than 1920 pixels will be enlarged to fit. Images wider than 1920 pixels will be cropped on both sides. Images taller than 1080 pixels will be cropped from top and bottom. It scales to 470 x 174 pixels tall in the feed.
Minimum image size: Facebook says that it should be “30,000 pixels in any dimension, and less than 135,000,000 pixels in total size.” Aspect ratio: 2:1
Tip: Facebook automatically recognizes and processes these images based on “camera-specific metadata found in photos taken using 360-ready devices.”
Recommended: At least 1,200 x 720 pixels—9:16 to 16:9 aspect ratio
Recommended: 1080 x 1920 pixels (but keep your text within 1080 x 1420)
Recommended: Maximum: 240 minutes
Recommended: 1080 x 1920 pixels
Recommended: 1200 x 628 pixels
Recommended: 1200 x 720 pixels
Recommended: 1200 x 30 pixels tall
NOTE: Facebook will scale photos that don’t meet minimum dimensions:
Square: Minimum—154 x 154 pixels in feed, but 116 x 116 pixels on the page
Rectangle: Minimum 470 x 246 pixels in feed, but 484 x 252 pixels on the page
Viewed on the group page: 820 x 462 pixels tall
Viewed on a desktop newsfeed display: 820 x 250 pixels tall
Tip: Note that what users see if they encounter your group on their newsfeed is going to be a cropped version of what they’d see on the page itself, so be sure to keep your key information centered within that “safe zone” in order for it to be fully viewed across channels.
At least 1080 x 1080 pixels
How to Create Great Facebook Cover Photos (Free Templates)
https://blog.hootsuite.com/facebook-cover-photos/
Facebook Header Template
https://docs.google.com/presentation/d/1fzfCFQUpZCbK2JIaHvyQG5spVhtBgZ3PQBcvs_B_Cfo/template/preview