Here's a handy infographic that shows you the recommended image sizes for all Facebook and Instagram ads. It’s brand new for 2016 and includes all of the new ad types including Lead Ads and Facebook Canvas!
Social Media Image Sizes for 7 platforms - updated June 16, 2014. All the essential sizes for Facebook, Twitter, Google+, LinkedIn, Pinterest, Instagram, YouTube. Plus links to more info and templates on the blog! -- http://louisem.com/2852/social-media-cheat-sheet-sizes