Turn long videos into clips for X
A good clip on X is a strong moment people want to quote: a sharp answer, a bold claim, a funny exchange. Reeltopus finds those moments in your recording, fits them to X's length limit, keeps the speaker centered and burns in captions. Reeltopus is in early access, so join the waitlist to try it.
X at a glance
- Length without a subscription
- Videos up to 140 seconds and 512 MB.Checked 17 October 2026 · Source
- Length with a subscription
- UnclearX's video help says subscribers can upload videos under 4 hours at 1080p (2 to 4 hours at 720p), up to 16 GB. Its Media Studio page says about 3 hours and 8 GB.Checked 17 October 2026 · Source
- Size and shape (web upload)
- UnclearAspect ratio from 1:2.39 to 2.39:1, minimum 32 × 32, maximum 1920 × 1200 (and 1200 × 1900), up to 40 fps and 25 Mbps. The 1900-pixel height is just under a full 1080 × 1920 frame, and Media Studio allows 60 fps.Checked 17 October 2026 · Source
- Looping
- Videos of 60 seconds or less loop automatically.Checked 17 October 2026 · Source
- Automatic captions
- In the iOS and Android apps, captions show automatically in the timeline when a video has them. X makes speech-to-text with Microsoft Azure, and not every video gets captions.Checked 17 October 2026 · Source
- Caption files
- Media Studio accepts .SRT subtitle files, and embedded CEA-608/708 captions.Checked 17 October 2026 · Source
- Post text
- Up to 280 characters. Subscribers can write longer posts, up to 4,000 characters according to X's How to Post page. Videos don't count toward the limit.Checked 17 October 2026 · Source
- Scheduling
- X Pro and Media Studio can schedule posts for a set date and time.Checked 17 October 2026 · Source
900 × 1440
What works on X
Fit the 140-second limit
Without a subscription a video can't run past 140 seconds. Pick moments that make their point well inside that, and check longer stories before exporting.
Keep the hook in the middle
In the timeline a vertical video shows much smaller than full screen until someone taps it. A centered face and a short caption line stay readable at that size.
Quote the clip in the post
Write the strongest line from the clip as the post text, so the post works even before the video plays.
Use short clips that loop
Clips of 60 seconds or less loop automatically, which suits quick reactions and one-liners.
How Reeltopus prepares clips for X
Clips that fit X's length
Ask for a length in plain words, like "under 2 minutes", or trim by deleting words in the transcript. The clip brain keeps the setup and the payoff together.
Captions you can rely on
X doesn't caption every video, so Reeltopus burns animated captions into each clip, with key words highlighted. SRT files are included for Media Studio.
Speaker kept in frame
Active-speaker tracking reframes 16:9 recordings to 9:16 and keeps the person talking near the center, with split screen for two-person conversations.
Transcripts in 100+ languages
Transcription handles 100+ languages, including mixed speech like Hinglish. Fix a word once and every clip that uses it updates.
Posting: Posting to TikTok, Instagram, YouTube, LinkedIn, X, Threads and Facebook is rolling out platform by platform, switching on as each platform's app approval completes. X switches on once its app approval completes. Until then, download the MP4 and post it on X yourself, or schedule it in X Pro or Media Studio, which works from day one.
Free tools
Video length and reading-speed calculator
Find out how long your script runs at your speaking pace, how many words fit a 15, 30 or 60-second clip, and whether your captions are too fast to read.
Aspect ratio and safe-zone calculator
Exact pixel sizes and UI safe zones for YouTube Shorts, Instagram Reels, TikTok, LinkedIn and X, plus a crop calculator and ffmpeg command for turning 16:9 video into 9:16.
Caption generator
Paste a transcript or script and get short-form caption lines for TikTok, Reels and Shorts, with a live animated preview and free SRT and VTT downloads. No sign-in.
Hook line generator
Paste a paragraph from your video or script and get 5 opening hook lines for TikTok, Reels and Shorts, written by AI. Free, no sign-in.
Questions
How long can a video on X be?
140 seconds without a subscription. Subscribers can upload much longer videos; X's help pages give up to 4 hours or about 3 hours depending on the page, at lower resolution past 2 hours.
What size should a video for X be?
X accepts aspect ratios from 1:2.39 to 2.39:1. Vertical 9:16 plays full screen when tapped but small in the timeline, so keep the speaker and captions in the middle of the frame.
Does X caption videos automatically?
X generates captions for some videos and shows them automatically in the mobile apps, but not every video gets them. Burned-in captions always show. In Media Studio you can also attach an SRT file.
Can I schedule video posts on X?
Yes, with X Pro or Media Studio. Pick a date and time when composing the post.
Is Reeltopus a Twitter video maker?
It makes clips from long videos: podcasts, talks, streams and webinars. You get captioned, speaker-tracked clips sized for X, ready to download and post. Direct posting to X is part of the platform-by-platform rollout.
Make X clips from every long video.
Join the waitlist for early access. The free plan includes 2 upload hours a month.