TikTok takes a standard MP4, but the vertical frame and the audio rules decide how the clip performs.
Save a video from X in a form TikTok will accept. TikTok takes a standard MP4, but the vertical frame and the audio rules decide how the clip performs. The download is a plain MP4 copied straight from X, with no watermark added and nothing re-encoded, which is exactly what TikTok wants as an input. Below: the requirements that actually matter, which resolution to pick, and the mistakes that cause an upload to be rejected or look soft.
TikTok accepts MP4 up to 10 minutes from the app and longer from the web uploader. H.264 with AAC audio is the expected combination, which is what every X download here already is.
The download here is an ordinary MP4 with H.264 video and AAC audio, which is the format TikTok is built around. There is no conversion step to get wrong and no container to fix.
Take 1080p whenever the post has it. TikTok compresses aggressively and visibly favours uploads that arrive at full resolution; a 720p source tends to come out soft after the platform has finished with it.
As a general rule, take the highest resolution the post offers. TikTok will compress whatever you give it, and starting from a better source means the compression has more to work with. Handing it a 480p file to save time produces a visibly worse result than handing it 1080p, because every stage of compression after that is working from less.
TikTok is 9:16. A landscape X clip uploaded untouched shows with large black bars, which the algorithm treats poorly. Crop to vertical first, or build the clip on a vertical background rather than letting the uploader pad it.
This is the single most common reason a re-shared clip looks wrong. Most X videos are landscape or square, because that is how they were filmed, and forcing one into a vertical frame either crops the sides off or leaves bars above and below. Neither is fixed by the download; both are fixed in whatever you crop with before uploading.
X does not brand the video files it serves, and nothing is added here either. What you download is what was published.
If you have seen watermarked downloads before, they came from a tool that added its own branding to advertise itself, not from X. That is worth avoiding for TikTok specifically: a visible third-party watermark reads as reposted content, which is the kind of thing recommendation systems quietly deprioritise.
Save the file to Photos or Gallery and it appears in TikTok’s upload picker. On Android the Downloads folder is usually enough; on iPhone move it into Photos first.
On a phone, the file lands in your Downloads folder or the Files app, and every app that accepts video can reach it from there. On a computer it goes to Downloads and can be dragged straight in. No import, sync or library step is needed in either case.
Reposting is where copyright actually bites. The person who filmed or posted the video owns it, and saving a copy does not change that, whatever platform it ends up on. Most platforms, TikTok included, will remove reposted content on a rights-holder complaint and may penalise the account that posted it.
Credit is not a licence, but asking is usually enough: many people are happy to have a clip re-shared if they are asked first. Saving a clip for yourself, or re-sharing your own posts across platforms, raises none of this.
Open the post on X, tap or click Share, then Copy link.
Drop the link into the field at the top of this page.
Take the highest resolution offered, then upload it to TikTok as you normally would.