Bluesky Video Length Limit Checker: Size and Format
Check a video against the Bluesky video length limit, the size limit and the accepted formats before you sit through the upload. Everything runs in your browser.
Bluesky video limits
A Bluesky post can hold one video up to 10 minutes long and 300 MB. The official app accepts MP4, MOV, WebM, MPEG and GIF files, and you can add alt text and up to 20 caption files. Images are separate: up to 4 per post, 2 MB each.
Drop a video file here
MP4, MOV, WebM, MPEG or GIF. The file stays on your machine. There is no upload request in this page.
Bluesky video requirements
| Property | Limit | Source |
|---|---|---|
| Length | 10 minutes | Bluesky app, VIDEO_MAX_DURATION_MS |
| File size | 300 MB (300,000,000 bytes) | app.bsky.embed.video lexicon |
| Videos per post | 1 | app.bsky.embed.video lexicon |
| Upload formats | MP4, MOV, WebM, MPEG, GIF | Bluesky app, SUPPORTED_MIME_TYPES |
| Stored format | MP4 | app.bsky.embed.video lexicon |
| Caption files | Up to 20 WebVTT files, 20,000 bytes each, one language per file | app.bsky.embed.video lexicon |
| Alt text | Separate field, no length cap in the lexicon since August 2026 | app.bsky.embed.video lexicon |
| Images (for comparison) | Up to 4 per post, 2,000,000 bytes each | app.bsky.embed.images lexicon |
Last checked October 10 2026 against the video lexicon and the Bluesky app constants. Other clients and self-hosted servers may set different limits.
What changed in 2026
Many pages still say Bluesky videos are capped at 3 minutes and 100 MB. That was true until August 2026.
- Before August 2026The standard cap was 3 minutes and 100 MB. Ten minute uploads existed only behind a feature gate in the app.
- August 11 2026The video embed lexicon raised the size limit to 300,000,000 bytes, noting it was formerly limited to 100 MB.
- August 14 2026The lexicon removed the character limit on video alt text.
- August 25 2026The Bluesky app removed the 10 minute feature gate, so the 10 minute cap now applies to every account.
Your file does not leave this device
There is no upload endpoint behind this page. Open the network panel in your browser dev tools, drop a file, and watch for a request that never comes.
Size and type come from the file
The browser already knows the byte count and the media type of a file you pick, so no part of the video has to be read for those two checks.
Length comes from a hidden player
A video element loaded from a local object URL reports duration, width and height. The URL is revoked as soon as the metadata is in.
Captions are only measured
Caption files are checked by name and byte size. Their text is never read or sent.
OpenTweet does not post video to Bluesky yet
OpenTweet posts text and up to 4 images to Bluesky. A post with a video can only go out on X for now. Use this checker, then upload the video in the Bluesky app.Schedule your Bluesky text and image posts
OpenTweet schedules Bluesky, X and LinkedIn posts from one draft or one API call. Bluesky connects over atproto OAuth, with no App Password.
7-day free trial, then from $11.99/mo. Bluesky on every plan.
Or read how the Bluesky scheduler works.
Bluesky Video FAQ
What is the Bluesky video length limit?
Ten minutes. The official Bluesky app made the 10 minute cap apply to every account on August 25 2026. Before that the standard cap was 3 minutes, with 10 minute uploads behind a feature gate.
What is the Bluesky video size limit?
300 MB, counted as 300,000,000 bytes. The video embed in the AT Protocol lexicon was raised from 100 MB to 300 MB on August 11 2026.
What video formats does Bluesky accept?
The official app accepts MP4, MOV (QuickTime), WebM, MPEG and GIF files. Uploads go through Bluesky's video service, and the post record itself stores an MP4.
How many videos can a Bluesky post have?
One. The video embed holds a single video. Images are a separate embed with up to 4 images of 2 MB each.
Can I add captions and alt text to a Bluesky video?
Yes. A video can carry up to 20 WebVTT caption files, each tagged with a language and up to 20,000 bytes. Alt text is a separate field, and the lexicon dropped its length cap on video alt text in August 2026.
Does OpenTweet post video to Bluesky?
Not yet. OpenTweet posts text and up to 4 images to Bluesky. If a post has a video, it can only go out on X. This checker is free to use either way.
Is my video uploaded anywhere?
No. The file is read in your browser. Length and dimensions come from a hidden video element loaded from a local object URL, and no network request carries the file.
Related tools and guides
Bluesky Image Checker
Check images against the 2 MB limit, shrink them in your browser and count alt text.
Bluesky Image Size Limit
How big a Bluesky image can be and what changed in 2026.
X Video Specs Checker
The same kind of check for video on X, including the H.264 codec test.
Bluesky Character Counter
Count graphemes and bytes against the 300 character Bluesky post limit.
Bluesky Scheduler
Schedule Bluesky posts over OAuth, with no App Password.
Cross-Posting
One draft to X, Bluesky and LinkedIn, counted per platform.