Facebook automatically scales the photos to fit the screen of the device you’re using, to 128 x 128 pixels (profile photo) and 640 x 360 pixels (cover photo).

The Facebook cover photo area is 851 pixels wide by 315 pixels tall. Photos uploaded for use as a cover photo must be at least 399 pixels wide. Like profile photos, these photos are resized to ...

It’s also now possible to use 360-degree images (from any source) as Cover Photos. This is the first ever update to format support Facebook has made for Cover Photos since its introduction.