Image courtesy of Kittisak
Each social media network has a specific requirement for header and user images. Not having the right dimensions will make your networks appear unflattering–and whether you are an individual user or business, that can be embarrassing since everyone sees it. Sizes are in pixels.
Twitter
Header Image: 1500 x 500
User Photo: 400 x 400 (It will display as 200 x 200)
In-stream Photo: 440 x 220
Facebook
Cover Photo: 851 x 315
Profile Image: Displays at 180 x 180
LinkedIn
Business Logo: 100 x 60
Career Cover Photo: 974 x 300
YouTube
Channel Cover Photo: 2560 x 1440
User Photo: Currently imported through Google+