Twitter

(Twitter does not support animated GIFs for profile or header images.)
 * Header photo (recommended dimensions are 1500x500 pixels)
 * Profile photo (recommended dimensions are 400x400 pixels)
 * Photos can be in any of the following formats: JPG, GIF, or PNG.

How many characters do photos and GIFs use?
None, photo and GIF attachments do not count towards the 140 character limit in a Tweet (in iOS, Android, twitter.com, and mobile web clients-only).

What are the size and file type requirements?

 * Photos can be up to 5MB; animated GIFs can be up to 5MB on mobile, and up to 15MB on web.
 * We accept GIF, JPEG, and PNG files.
 * We DO NOT accept BMP or TIFF files.
 * Your photo will be automatically scaled for display in your expanded Tweet and in your gallery.

Video files must meet all of the following criteria:
 * Duration should be between 0.5 seconds and 30 seconds (sync) / 140 seconds (async)
 * File size should not exceed 15 mb (sync) / 512 mb (async)
 * Dimensions should be between 32x32 and 1280x1024
 * Aspect ratio should be between 1:3 and 3:1
 * Frame rate should be 40fps or less
 * Must not have open GOP
 * Must use progressive scan
 * Must have 1:1 pixel aspect ratio
 * Only YUV 4:2:0 pixel format is supported.
 * Audio should be mono or stereo, not 5.1 or greater
 * Audio must be AAC with Low Complexity profile. High-Efficiency AAC is not supported.