How to add captions to a video on X
By the maker of Captions Cut. Facts checked on from the pages listed under Sources.
The short answer
X generates captions with speech-to-text and shows them when a viewer’s captions setting is on, and lets you attach an SRT file on the web. Without X Premium a video can be up to 140 seconds and 512 MB. Burned-in captions made with Captions Cut show for everyone, whatever their captions setting.
X (Twitter) video limits
| X (Twitter) | |
|---|---|
| Length | Up to 140 seconds and 512 MB; with X Premium, up to 4 hours at 1080p and 16 GB. |
| Shape | 1:2.39 to 2.39:1 on the web; 9:16 recommended for vertical ads. |
| Resolution | Up to 1920 × 1200 (or 1200 × 1900) on the web. |
Captions built into X (Twitter)
- X generates captions with Microsoft Azure speech-to-text.
- Viewers see them according to their device’s accessibility setting, or the CC switch on the web.
- You can attach your own .srt file when posting from the web.
Caption files. X takes SubRip (.srt) files, on the web only.
Where captions are safe
X publishes no safe zone for video in the timeline; its player controls sit at the bottom. Captions Cut keeps captions inside the area the vertical apps leave clear: below the top bar and above the caption, buttons and username at the bottom. Drag them anywhere if your shot needs it.
Burn captions into a video on X with Captions Cut
- Open captionscut.com/edit in a browser, or the Captions Cut iPhone app, and add the clip.
- Choose the spoken language or leave it on Auto detect (53 languages), check the cost (1 credit per second of audio) and create the captions.
- Read the transcript and tap any word to fix it.
- Pick one of 48 styles and place the captions clear of the app’s buttons.
- Export in 1080p or 4K and post it to X (Twitter).
The video stays on your device: only the audio is sent for transcription, and it is deleted right after.
Platform captions or burned-in captions?
| Built into X (Twitter) | Burned-in captions | |
|---|---|---|
| Who sees them | Viewers who have captions on | Everyone, including on reposts and downloads |
| Style | The platform’s | Yours: font, colour, word-by-word highlight |
| Fixing mistakes | In the platform, after posting | Before posting, word by word |
| Search and accessibility tools | Readable as text by the platform | Part of the picture; add a caption file too where the platform takes one |
How we checked
Every X (Twitter) fact on this page comes from the platform’s own help, ads or developer pages, read on 22 October 2026. Where a page says nothing (a language list, a safe zone), this page says so rather than guess. Ads-guide numbers are for ads; organic posts have the same buttons in the same places.
Questions
How long can a video on X be?
140 seconds and 512 MB without a subscription; up to 4 hours with X Premium.
Sources
Each page read on .