Every big social media network available nowadays like: Facebook, Twitter, Google Plus, Linkedin etc., monetize their trafic by different types of ads. Because of this different types of social ad sizes, marketers are confused when they want to make more paid campaigns on different social networks simultaneously. The guys from Flightpath made an useful social media ad image sizes cheat sheet 2014 infographic which you can see below. If you are planning to start a new social media paid campaign on Facebook, Twitter, Google Plus or Linkedin and get the best ROI from this ads, you better have a clever copy and some optimize images for mobile and desktop devices.
This social media ad image sizes infographic contains the Instagram ad size too, but for the moment, advertising on this photo sharing social network is opened only to a few advertisers.
See also: The Ultimate Guide to Best Times to Post on Social Media (Infographic)