Short answer
Use short promoted videos (aim for 15 seconds or less) in 1:1 or 16:9 for the timeline, 9:16 for vertical video ads, with captions, your brand and message in the first seconds, and a clear call to action.
Key takeaways
- Most people watch with sound off: caption everything.
- Square or landscape for timeline ads, vertical for the vertical feed.
- Hook in the first three seconds; brand early.
Video is the format X has pushed hardest since its vertical video feed launched. Good video ads on X are short, readable without sound and clear about who made them.
Which video ad formats exist?
Promoted video in the timeline, Vertical Video Ads in the full-screen feed, and Amplify pre-roll before publisher videos.
| Format | Where it plays | Shape |
|---|---|---|
| Promoted video | Timelines, search, profiles | 1:1 or 16:9 |
| Vertical Video Ads | Full-screen vertical feed, sound on | 9:16 |
| Amplify Pre-roll | Before videos in chosen content categories | 16:9 typically |
What makes a video ad work?
A hook, early branding, captions and one message.
- First three seconds: movement, a face or a bold line of text. People decide fast.
- Brand early: logo or product in the first few seconds, not only at the end.
- Captions: most timeline viewers have sound off.
- One message: one benefit, one call to action.
- Length: 6 to 15 seconds for most ads; longer only when people want detail.
What specs should I follow?
MP4 or MOV, H.264, at least 720p, square, landscape or vertical depending on placement.
X publishes exact limits (file size, maximum length per advertiser type) on its creative specifications page and updates them; check it before final export.
How do I test?
Run two or three cuts against each other: different hooks, lengths or captions.
Keep everything else equal and compare cost per view or per click. Then reuse the winning hook in new creative. For campaign setup, see running X ads.
How do I write the post text for a video ad?
Short, specific and consistent with the video: the text should tell people why to watch.
- Lead with the benefit or the hook from the video, not the brand name.
- Keep it to one or two lines; the video is the main event.
- Include one call to action that matches the button (Shop, Learn more, Install).
- Avoid hashtag piles; one branded or campaign tag is enough.
Mock up the post with the generator's video poster and Ad label before buying, so stakeholders see the ad as people will.
Questions people ask
How long can an X video ad be?
X allows long videos for many advertisers, but short performs better. Aim for 6 to 15 seconds for most timeline ads; longer works for tutorials and launches.
Which aspect ratio is best?
1:1 square or 16:9 landscape for the timeline; 9:16 for Vertical Video Ads. Square takes more screen space on phones.
Do I need captions?
Yes. Timeline videos usually autoplay muted. Burned-in captions or an uploaded caption file make the message clear without sound.