For one video, X does not keep a single file. It publishes the same video several times over, at different sizes, and hands each viewer whichever one suits their screen and their connection. We list all of them and let you choose.
What that looks like on a real post
Measured on a public post from NASA, three minutes and twenty-five seconds long:
- 720p — 17.9 MB, the biggest size X published for it
- 360p — 6.7 MB
- 270p — 2.7 MB
And on a one-minute post from SpaceX: 1080p at 8.6 MB, 720p at 4.8 MB, 360p at 1.8 MB. Those numbers are not estimates — they are what the file server answers when asked, and they are the ones shown next to each button before you save anything.
Why 4K is rare
A post only offers 4K if its author uploaded 4K and X kept it, which is uncommon. No tool can create detail that was never published: a site advertising 4K for every video is selling you an upscale, which is a bigger file holding the same picture.
Why the phone shortcuts stop at 1080p
The iPhone shortcut and the Telegram robot pick the best size up to 1080p rather than the absolute biggest. On a phone screen the difference is invisible, the file is a fraction of the size, and it lands in seconds instead of minutes. On this page you get the full list and the last word.
Sound on its own
The one format that is not a file from X: we build it. The MP3 page has the bitrate, the limits and how close the announced size lands.