LinkedIn Banner size
LinkedIn banner looks like the cover on top of your LinkedIn profile and should be 1584 pixels long by 396 pixels. Keep the banner high quality and all the graphics elemnets visible.
LinkedIn Banner format
LinkedIn banner should be JPG or PNG file that weighs less than 8MB, for images with a logo or text, it might be best as a PNG file.
Why your LinkedIn Banner matters
LinkedIn banner is a small but significant tool as it conveys your skills, experience, brand, and person.
Besides, people notice it when they visit your profile first.