Twitter Header Images are the large horizontal images that structure the top of every Twitter Profile. Used commonly as a space that can grab the attention of a visiting Twitter User, Twitter Header Images pair with the Twitter Profile Image to further curate an aesthetic, statement, or expression of the Twitter Profile. Twitter Header Images have a 3:1 aspect ratio and are sized at 1500 x 500 pixels with a maximum file size of 5 MB. Twitter Header Images can be uploaded in JPG, PNG, or GIF formats. Animated GIFs are not supported.
Twitter In-Stream Images are images that can be attached to any Tweet and will appear on the Twitter feeds of followers. Accepting up to 4 images per Tweet, Twitter In-Stream Images no longer count against the character count of a Tweet and are widely used to accompany news stories, articles, and event announcements. Twitter In-Stream Images have a horizontal aspect ratio of 16:9 and are sized at 600 x 335 pixels with a maximum individual image size of 5 MB. Twitter In-Stream Images can be clicked and expanded to up to 1200 x 675 pixels. JPG, PNG, GIF, and animated GIF formats are accepted.
Width (Expanded): 1200 px
Height (Expanded): 675 px
Aspect Ratio: 16:9
Format: JPG, PNG, GIF
Max Size (Photos/GIF): 5 MB
Max Size (Web): 15 MB
Twitter In-Stream Image layout, Twitter icon