Graphics Design: Social Media
SEE THIS FOR SOCIAL MEDIA SIZES (2015 edition): Social Media Image Size Cheat Sheet
Social Media Icon
Twitter, Facebook and Tumblr can all use the same icon. It must be square. 2014's icon was 877x877 pixels, and 2015 was 765x765. It should generally be as large as possible and can just be a crop of the flier.
This is generally a closeup on the year's mascot's head (or a mascot if there are more than one).
Facebook header
Facebook header is 851x315. For 2015 I used this as a template, although a screenshot of facebook would also have worked as a template.
Facebook event header
The event header for Facebook is different than the header for the Facebook page and needs to be specially designed for specific placement of items.
It would be best to look at last year's header file to start the current year. This is also a good place to start as it shows you the pixel sizes for things and what they're used for. It helps to use it as a layer in the file to reference and set guides and whatnot, as well.
Twitter header
There is a template in the dropbox for the 2015 header. It was downloaded from here.
Tumblr
I generally recycle the other SM images for Tumblr since all the services are similar.
Tumblr Header
In 2015 we used the same file as the Facebook Event page. Because it's size is 2/3rds the size of the event banner we can just move it to one side or the other and it seems to fit fine.
Tumblr Banner
I use the same banner as the Facebook Page banner. If I have time I will alter it so that the URL is not so high and move center content a little to the left. If in a rush - it's okay to use the Facebook banner with no changes.