Bluesky Video Upload Checker

Bluesky's current video limits

The checker compares your file with the limits in Bluesky's own published source code and schemas.

• Maximum file size300,000,000 bytes (300 MB).
• Maximum duration10 minutes (600 seconds).
• Formats listed in Bluesky's appMP4, MPEG, WebM, QuickTime (MOV) and GIF.
• Videos per postOne. The schema's video embed holds a single video file.

These come from two places. The Bluesky app's source code sets the size, duration and format list. The post schema describes the stored video as one MP4 file of up to 300,000,000 bytes and notes that the limit was formerly 100 MB. The schema has no duration field, so the 10-minute limit is defined in the app's code rather than in the post schema.

Last verified: 1 October 2026 against Bluesky's official source: social-app · src/lib/constants.ts (video size, duration and supported types), app.bsky.embed.video and app.bsky.feed.post. Limits can change, so check the sources if this date is old.

Why check the actual file

Specification tables go stale. The post schema itself still notes that its video limit was formerly 100 MB, and older guides keep repeating smaller numbers. Checking your real file removes the guesswork: you see the size, duration and dimensions Bluesky would receive, compared with the current limits.

Units matter too. Bluesky's source code defines its maximum in decimal megabytes: 300 × 1,000 × 1,000 bytes. A file manager that reports binary mebibytes can make a file that is over the limit look as if it fits, so this page shows the exact byte count and compares it with 300,000,000.

What it does not guarantee

• That an upload will succeed. Codec, bitrate, account status and Bluesky's own processing are outside what a browser-only check can see.
• The same result everywhere. Other Bluesky apps, third-party schedulers and browsers can apply their own limits or read files differently. SkyyCast's scheduler, for example, accepts one MP4 video per post with its own size limit, which can be lower than Bluesky's. The composer shows the current limit.
• The real format. The format shown is the type your browser reports, cross-checked against the first bytes of the file. It is not a full inspection, and a file's extension alone proves nothing about what is inside.
• Metadata for every file. Browsers cannot read every format, so a valid video can still show its duration or dimensions as unavailable. The tool says so rather than guessing.
• Any resolution or aspect ratio requirement. Dimensions and aspect ratio are shown for information only. The limits this tool checks do not set one.

Privacy first

Your video is read and measured by your own browser. It is not uploaded to SkyyCast, stored, or sent to any other service, and no account is needed. The summary you can copy contains measurements only, never your file name. Closing or reloading the page discards everything. (Like the rest of the site, the page loads its font from Google Fonts.)

More free Bluesky tools

See all free Bluesky tools. Checking a whole post? The Bluesky Post Validator checks its text and images, and the Bluesky Image Size Checker prepares oversized images.

About this tool

SkyyCast is an independent third-party service. It is not affiliated with, endorsed by or sponsored by Bluesky. The name “Bluesky” is used only to describe which service the tool checks videos for.