Slack's help centre states one file upload limit, and it states it unconditionally: "You can add files up to 1GB in size." That sentence sits at the top of the "Add files to Slack" article, and the page it sits on contains no per-plan table for per-file uploads — no Free row, no Pro row, no Business+ row, no Enterprise+ row.
That is worth saying out loud, because most results for this query show a tiered table: 1GB on Free, 10GB from Pro, unlimited on Enterprise. Slack does not publish those tiers. If you are asking whether upgrading lets you send a bigger file, the documentation never says it will.
Other numbers do exist — 5GB, 50MB, five minutes, 90 days — each real, and each governing something other than how big a single file can be. Most of the confusion here comes from them being shuffled into the wrong column.
The limits, at a glance
| What it governs | Official value | Source |
|---|---|---|
| Single file upload | 1GB | Help centre, "Add files" |
| Per-file limit by plan | not published | — |
| Files per drag-and-drop | "up to 10 files" | Help centre, "Add files" |
| Image inline preview, longest side | "smaller than 25,000 pixels" | Help centre, "Add files" |
| Image inline preview, total pixels | "less than 45 million pixels total" | Help centre, "Add files" |
| Office file preview | none when "larger than 50 MB" | Help centre, "Add files" |
| Audio/video clip length | "up to five minutes long" | Help centre, clips article |
| Free workspace storage ceiling | 5GB uploaded, via storage_limit_reached | Developer docs, error table |
| Free plan visibility window | "the last 90 days" | Help centre, free usage limits |
| Free plan permanent deletion | "more than one year old" | Help centre, free usage limits |
| Duration limit for an uploaded video file | not published | — |
| Recommended resolution, bitrate, frame rate | not published | — |
Every "not published" row is one where Slack's documentation says nothing. If you need one of those numbers, check the official documentation — nobody quoting a figure for them is quoting Slack.
The three numbers people mix together: 1GB, 5GB, 50MB
These three get used interchangeably. They are not.
1GB is the per-file upload ceiling. It is the only number Slack attaches to adding a file, and the text carries no conditions.
5GB is a whole-workspace total on free teams, and its only source is developer documentation. The files.getUploadURLExternal reference lists an error code, storage_limit_reached, described as: "File storage limit has been reached. This occurs when free teams have uploaded 5GB of files." A 2019 developer changelog dates enforcement to March 5, 2019, with files beyond the limit returned by the API as "mode": "hidden_by_limit". Two things follow. It is a cumulative workspace total, not a per-file rule. And it lives in an API error table, not on a user-facing page; today's help centre describes free-plan limits in terms of time (90 days, one year), not capacity.
50MB is a preview threshold, and only for Microsoft Office files. The help centre: "Microsoft Office files that are larger than 50 MB will not display a preview." The threshold is about the preview, not about whether the upload succeeds.
That generalises: preview rules and upload rules are separate systems in Slack. An image preview "will only display inline if it's smaller than 25,000 pixels on the longest side, and less than 45 million pixels total." Note the "and" — both conditions must hold. A 30,000 × 1,000 panorama is only 30 million pixels, inside the second condition, and still will not display inline because it breaks the first.
Why an upload can fail when you are nowhere near 1GB
Size is the obvious cause and often not the real one. Four documented reasons, worth checking in this order:
- Your admin tightened the limit. The same error table includes
file_upload_size_restricted: "The size of provided file is too large, as the team has restricted uploads of large files." So 1GB is Slack's ceiling, not necessarily your workspace's. Slack does not document where that setting lives — ask a workspace owner or admin. - The file was scanned and blocked. Slack states that files added to Slack are scanned for viruses and other malware and "won't be uploaded if any are detected" — and asks you to contact them if a file is blocked incorrectly.
- You are in a Slack Connect conversation. Slack warns that "Uploading and sharing files may be restricted for Slack Connect conversations, and certain file types can't be added at all."
- The workspace is out of storage — on a free team, the
storage_limit_reachedcase above.
What to do when a file genuinely is too big
For video, Slack's documentation says nothing about whether it transcodes or re-compresses what you upload, or about whether the size check happens before or after any such pass. Treat the file you hand Slack as the file that gets measured.
So re-encode before uploading.
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
This runs inside your browser tab: the file is read from disk, re-encoded locally, handed back. Nothing is uploaded to a server, which matters when the thing you are sharing is an internal recording — no second copy on somebody else's machine. To understand the trade rather than accept a preset, how to compress a video without losing quality covers what bitrate and resolution actually do. For a QuickTime file off a Mac or iPhone, MOV to MP4 swaps the container, and all Clapr tools lists the rest.
Slack-specific gotchas
Zipping a big video for Slack Connect makes things worse. Slack lists file types that "cannot be added to Slack Connect channels and direct messages (DMs)", and it includes .7z, .gz and .tar — but not .mp4, .mov, .mkv or .webm. The instinct to archive a large video before sending is exactly backwards: the raw video is allowed, the archive is not. Keep the qualifier straight — that list covers Slack Connect conversations, not Slack as a whole.
Five minutes is a clip limit, not a video limit. Clips are for sharing "audio and video clips up to five minutes long in Slack", available "on all plans". Slack publishes no duration limit for a video file uploaded normally — only the 1GB size limit. The clips article mentions you can "Upload an existing video as a clip", but never states which containers, codecs or sizes that path accepts.
On mobile, you can only download images. From the help centre: "On your mobile device, you can only download image files." If a colleague needs that video on their phone, Slack's own path does not get there.
Sharing a file outside Slack by link is paid-plan only, per the help centre.
The codec list you may have seen is for huddles. Slack says huddles "rely on AV1, VP9, and H.264 for media encoding and decoding" — that governs real-time calls, not uploaded files.
The free-plan trap that costs people their files
On the free plan two different mechanisms are at work, and only one is reversible.
90 days is hiding. Slack: "When your workspace reaches the visibility limit, Slack will start hiding messages and files older than 90 days to make room for new ones." Hidden is not gone — upgrade and "the remaining 275 days will become available."
One year is deletion. The same page: "Messages and files more than one year old will be permanently deleted." And on recovery: "It will not be possible to restore messages and files once deletion occurs." Starting August 26, 2024, Slack says such content "may be deleted on a rolling basis" from free workspaces.
And here is the trap. Workspace Owners choose between two retention settings — keep everything for a year, or delete after 90 days. Slack spells out what the second choice does: "If you choose to delete messages and files after 90 days, this will automatically delete any that become hidden by the message and file limit." Pick it and the 90-day hiding stops being reversible: upgrading later brings nothing back, because it was deleted, not hidden.
FAQ
What is Slack's file upload limit? 1GB per file, stated without conditions in Slack's "Add files to Slack" article. You can drag and drop "up to 10 files" at once.
Does Slack's file size limit increase on Pro or Enterprise plans? Slack's documentation does not say so. The 1GB figure is published with no plan attached, and that page carries no per-plan table for per-file uploads at all. The tiered numbers circulating online have no official source — check the official documentation before upgrading for that reason alone.
Why does Slack say my file is too large when it is under 1GB?
Slack's documentation does not rank the causes. One documented possibility is that your workspace tightened the limit: the developer docs list a file_upload_size_restricted error, "The size of provided file is too large, as the team has restricted uploads of large files." On a free workspace the other candidate is the storage ceiling, storage_limit_reached.
How much storage does a free Slack workspace get? The only figure with an official source is 5GB, and it appears in developer documentation as an error condition, not a product promise. Today's user-facing pages describe the free plan in terms of time instead: 90 days visible, permanent deletion after one year.
How long can a video be on Slack? Five minutes applies to clips. For an uploaded video file, Slack publishes no duration limit — only the 1GB size limit.
Why doesn't my file show a preview even though it uploaded? Preview rules are separate from upload rules. Microsoft Office files "larger than 50 MB will not display a preview", and an image only displays inline if it is "smaller than 25,000 pixels on the longest side, and less than 45 million pixels total" — both conditions, not either. The upload still succeeded.
For the same breakdown on other chat platforms, see what actually counts as "file too large" on Discord and WhatsApp video too large to send, or browse the rest of the platform limits guides.
All figures quoted from Slack's official help centre and developer documentation, checked 16 September 2026. Slack has revised these pages before — verify against the source before relying on them.
