Max file size for Slack: the 1 GB limit, the 90-day catch and what to do when an upload fails

Slack's max file size is 1 GB per file, with up to ten files in one message, and that number is the same on Free, Pro, Business+ and Enterprise. The limit that actually bites on a free workspace is not size but time: you can only see files from the last 90 days, and anything older than a year may be deleted. Here is what Slack's help pages say as of 5 Oct 2026, why uploads under 1 GB still fail, and what to do when they do.

Slack file limits by plan

The old advice to "free up storage" on a free workspace is out of date. There is no storage meter to empty. The free plan rolls forward on a 90-day window, and when a workspace reaches it Slack hides the oldest messages and files to make room for new ones. Nothing you delete brings a file back into view; only upgrading does, and only for data that has not yet been removed under the one-year rule.

Why an upload under 1 GB still fails

1. The connection, not the limit

A 900 MB upload from a laptop on hotel Wi-Fi fails for ordinary reasons: a dropped socket, a laptop sleeping, a VPN reconnecting. Slack shows the same "upload failed" message whether the cause was the network or the file. Retry on a stable connection before assuming the file is the problem.

2. The high-volume brake on free workspaces

Slack's free-plan page says the free version restricts use for storage and spam, and that you may be prevented from sending too many messages or files in a short period. A bot or an integration posting attachments in bulk can trip this for everyone in the workspace.

3. Workspace and org policies

Admins on paid plans can restrict which file types can be shared, block uploads from unapproved devices, or route files through a data-loss-prevention tool. The upload is rejected before it ever meets the 1 GB ceiling, and the error rarely says why.

4. The file is right at the edge

A file that reads 1.0 GB in Finder or Explorer can be a few megabytes over the real limit once it is measured in bytes. Shave the file or zip it to get safely under.

What to do when the upload fails

1. Retry once on a stable connection. Most failures are transient.
2. Check the size in bytes. Anything within a few megabytes of 1 GB should be trimmed or zipped.
3. Compress if it is media. A scanned PDF often drops by 80% through our free Compress PDF tool, in the browser, with nothing uploaded. Video can be re-exported at 720p.
4. Over 1 GB, or needs to outlive the thread: share a link. Upload the file once, paste the URL, and Slack unfurls it into a preview card. The per-file limit does not apply to a link, the 90-day window does not hide it, and the same URL works in every channel, DM and external Slack Connect conversation.

That last step is what Link in Seconds is built for. Drop a file in, get a clean link, paste it into Slack. The link never expires on any plan, you can swap the file behind it when a new version lands without re-posting, and the view count tells you whether anyone opened it. It also opens for a client or contractor who is not in your workspace at all, which an attachment never does. For many files at once, one shared folder link beats a ten-attachment message.

Slack versus the other apps

Slack's 1 GB is generous next to chat and email. Discord allows 20 MB free, Gmail about 18 MB once encoding overhead is counted, and WhatsApp recompresses anything sent through the media picker. Where Slack is weaker is retention: on the free plan an attachment is reliably findable for 90 days, which is shorter than any email inbox. The full comparison, with the hidden second limit for each app, is in file size limits by app.

Quick answers

Go deeper

• Every app's file size limit, and the second limit each one hides
• Max file size for Discord: free, Nitro Basic and Nitro
• Share files online as one link