A screen recording can be refused by Slack for three different reasons, and the error rarely tells you which one you hit. Slack documents a per-file upload ceiling, a separate time limit that applies only to clips, and a restricted file-type list in Slack Connect that blocks exactly the archive formats people reach for when something is too big to send.
Here is how to tell them apart — and in one case, the instinctive fix is what causes the failure.
Wall one: the 1GB per-file ceiling
Slack's help page on adding files states the upload limit in a single unconditional sentence:
"You can add files up to 1GB in size."
Two things about that sentence get misreported.
It carries no plan qualifier. That line sits at the top of the "Add files" article, on a page with no per-plan table for per-file uploads — no separate Free, Pro, Business+ or Enterprise+ row. Figures claiming paid plans get a bigger per-file allowance have no basis there. For a specific workspace, check the current limit in Slack's official help center.
It says nothing about duration. There is no documented length limit for a regular video file upload. A ninety-minute recording is fine by this rule if the file is under the ceiling. Length only becomes a hard limit when you send the recording as a clip — which is wall two.
The ceiling can be lower than 1GB on your workspace
If your recording is nowhere near 1GB and Slack still refuses it, there is a documented reason. Slack's developer reference for files.getUploadURLExternal lists this error:
"file_upload_size_restricted" — "The size of provided file is too large, as the team has restricted uploads of large files."
In other words, a workspace can be configured to refuse files well below the published limit. Slack's documentation gives the error text but not the admin setting behind it, so ask an owner or admin.
One more non-size reason worth ruling out. The "Add files" page notes:
"Files you add to Slack will be scanned for viruses and other malware, and won't be uploaded if any are detected. If we incorrectly block a file upload, contact us and we can help."
The fastest fix: shrink the recording before Slack sees it
Slack's documentation does not say whether it re-encodes or compresses uploaded video, or at what point any size check happens — so there is nothing to rely on there. Make the file smaller yourself before sending it.
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
This runs inside your browser tab: the recording is read from disk, re-encoded locally, and handed back to you. Nothing is uploaded to a server. For the trade-offs behind a preset, how to compress a video without losing quality covers what bitrate and resolution actually do to a screen recording. macOS screen captures usually land as QuickTime files, and MOV to MP4 swaps the container without a round trip. The full set lives at all Clapr tools.
Wall two: five minutes, but only for clips
Slack's built-in recording feature has its own ceiling. The help page on audio and video clips opens with:
"Share audio and video clips up to five minutes long in Slack to communicate easily with your team, regardless of their time zone or location. Anyone in a channel or direct message (DM) can play clips and reply in thread with a clip of their own."
Same page, under "Who can use this feature?": "All members and guests", and "Available on all plans". So this is not a free-plan restriction you can pay your way out of.
Keep these two numbers in separate boxes. Five minutes is the clip limit; 1GB is the file upload limit. They are different mechanisms attached to different features, and conflating them produces two wrong conclusions:
- "Slack won't take videos longer than five minutes" — false about file uploads. Slack documents no duration cap for those.
- "My clip should be fine, it's under 1GB" — the clip path has its own rule, measured in minutes, not megabytes.
The clip feature also lists "Upload an existing video as a clip" among its options. Slack's documentation does not state which containers or codecs that path accepts, or whether it applies its own size or length threshold, so do not assume a file that uploads normally will also go through as a clip.
One footnote that catches people out later: "Clips follow the same retention policy as other files in Slack."
Wall three: archiving it is what breaks it
When a recording will not upload, the reflex is to pack it into an archive — .7z, .gz, .tar — and send that instead. In a Slack Connect conversation, that reflex turns a file Slack would have accepted into one it refuses outright.
Slack's page on restricted file types in Slack Connect states:
"To help keep Slack secure, certain types of files cannot be added to Slack Connect channels and direct messages (DMs)."
The blocked extension list on that page includes .7z, .gz and .tar, alongside executables and scripts. It does not include .mp4, .mov, .mkv or .webm. The practical consequence is backwards from what most people assume: the raw recording is an allowed file type, and the archive you wrapped it in is not.
The "Add files" page flags the same territory from the other direction:
"Uploading and sharing files may be restricted for Slack Connect conversations, and certain file types can't be added at all. If you can't add files to these conversations, find an owner or admin and ask for help."
Do not stretch this rule further than it goes. That restricted list applies to Slack Connect channels and DMs — shared conversations with people outside your organization. It is not a workspace-wide ban list. If a specific extension is refused, check the current list in Slack's official documentation before concluding you have a size problem.
The working conclusion for screen recordings: send the video file, compressed — not an archive containing it.
"It uploaded but there's no preview"
Worth separating, because it looks like a half-failure and isn't one. Slack's documented preview rules are:
| Condition | Documented threshold |
|---|---|
| Image displays inline: longest side | smaller than 25,000 pixels |
| Image displays inline: total pixels | less than 45 million pixels total |
| Microsoft Office file shows no preview | larger than 50 MB |
Both image conditions must hold — the official wording joins them with and, so failing either one drops the inline display. These are display rules, not upload rules: a file that renders no preview still uploaded fine. Slack documents no equivalent threshold for video, so applying the image numbers to a screen recording is guesswork, not a limit.
How to tell it worked
If the compressed file is comfortably under 1GB and the upload still fails, size is probably not your problem. Two questions remain: is this a Slack Connect conversation where you are sending an archive, and are you going through the clip path with something longer than five minutes?
FAQ
Why is my screen recording too large to upload to Slack?
Most often it is over the documented per-file ceiling — Slack's help center says "You can add files up to 1GB in size." But a workspace can be configured more strictly: Slack's developer docs list a file_upload_size_restricted error for teams that "restricted uploads of large files." Compress the recording first, and if it still fails well under 1GB, ask an admin.
What is Slack's video length limit? Five minutes applies to clips — Slack's clip documentation says "Share audio and video clips up to five minutes long in Slack," on all plans, for members and guests. For a regular video file upload, Slack's documentation does not state a duration limit at all. The limit there is file size.
Why won't Slack let me upload a .7z of my recording?
In Slack Connect channels and DMs, certain file types are blocked entirely, and the published list includes .7z, .gz and .tar. Video extensions like .mp4 are not on that list. So archiving a recording to send it can turn an acceptable file into a rejected one. Send the compressed video itself. Note this list applies to Slack Connect conversations, not your internal channels.
Does Slack compress my video for me? Slack's documentation does not say whether uploads are re-encoded, or when any size check happens relative to that. Do not plan around it — send the file at the size you want people to receive, the same conclusion that applies on Discord.
Can I download a video someone posted in Slack to my phone? Not through the documented path. Slack's help page on downloading files says that on your mobile device, "you can only download image files." Use desktop for video.
I trimmed the recording and it's still huge. What now? Trimming shortens the recording; re-encoding is what lowers the bitrate, and that is usually where the size is. Start with the video compressor, and if you only need the spoken content, extract the audio and post that instead.
Quotes taken from Slack's help center pages on adding files, recording audio and video clips, and restricted file types in Slack Connect, plus the files.getUploadURLExternal reference in Slack's developer documentation, checked 16 September 2026. Slack revises these pages — verify before relying on them. More in the fix guides hub, and the published figures are collected in Slack's file upload limit, explained.
