As we know the rules and specs change regularly, but as of 2/25/2014 – this is the current list and dimensions. I can help you create your package of these or templates so you can edit after you have the first set.
Google Plus Profile Picture template (250 x 250)
New Google Plus Cover (1080 x 608)[infobox]
Don’t forget with each image to add a DETAILED description – take it as another opportunity to “post” about your business.
Google Plus “Lower Third” template for Google Hangouts On Air (1280 x 720)
I can teach you about setting up “profiles” on Hangouts if you have a few lower third custom overlays that you need. I am told I make fabulous lower thirds.
Google Plus Event Header template (1200 x 300)
Need an image for EVERY event or it looks boring – brand it, brand it!
YouTube Cover (2560 x 1440)
YouTube Cover Desktop Banner “Safe Area” (1546 x 423)
This is a tricky one as it needs to be created to allow for banner view wide, narrower, Television and mobile – one of the trickier ones to create.
Are you sending out a link to your video? Remember, you cannot embed video in email, but you can have a screen shot and insert it into the email and link to the video.
If you are really into Hangouts and video, I can design a background for you and send it to your local sign maker.
OK, time to leave the Google world and move on to the other venues:
Formats: Gif, Jpg, Png
LinkedIn Cover Desktop Banner (646 x 220)
LinkedIn Profile Picture (100 x 60)
Twitter Background Image (2560 x 1600) – mess with screen sizes it will change what is seen and covered
Twitter Header Image (520 x 260) – another tricky one based on screen size – test a few or ask for help. Happy to create this for you.
Twitter Profile Picture (81 x 81)
Facebook Cover Image (851 x 315) don’t forget to adjust for where profile pic covers part of the banner.
Facebook Profile Picture (180 x 180)
Facebook Event Banner Image (714 x 264)
Facebook Minimum Shareable Image (200 x 200)
This is the minimum size and image must be to be included in the list of images it will offer the user when they share the web page on Facebook.