Slack lets members and guests add files up to 1GB each, and you can drag and drop up to 10 files into one message. Previews have their own caps: Microsoft Office files over 50 MB won't show a preview, and some file types can't be added at all.
The numbers that decide whether a file goes through
If you've ever watched a progress bar crawl and then stop, this is the table you want. Every row comes from the Slack Help Center article on adding files, which says the feature itself is available on all plans.
| Item | Limit | Applies to |
|---|---|---|
| Maximum size of one uploaded file | 1GB | Members and guests |
| Files per drag and drop | Up to 10 files | The message field on desktop |
| Inline image preview, longest side | Under 25,000 pixels | Shared images |
| Inline image preview, total size | Under 45 million pixels | Shared images |
| Preview for Office files | No preview over 50 MB | Microsoft Office files |
Two separate things are going on here. The 1GB cap decides whether a file can be uploaded at all. The preview caps only decide whether people see the file inline in the conversation. A big Office file over 50 MB will still upload under the cap; it just won't show a preview, so your colleague has to download it to look inside.
What happens when an upload is refused
A file over 1GB won't upload, and there's no splitting or compression done for you. But size isn't the only reason a file gets turned away. The help article lists three others:
- A malware scan. Files are scanned for viruses and malware and aren't uploaded if anything is detected.
- Blocked file types. Certain file types can't be added at all.
- Admin restrictions. Uploading and sharing may be restricted in Slack Connect conversations and for Frontline Members.
1GB is a ceiling, not a promise
This is the part that catches agencies out. If you share a channel with a client through Slack Connect, or your team includes Frontline Members, an admin can restrict uploads, so the 1GB cap is the most you'll get, not what you're guaranteed. If a file that's well under the limit keeps failing in a shared channel, the fix sits with an owner or admin on whichever side set the restriction, not with you retrying the upload.
Sending files that are bigger than 1GB
For anything over the cap, upload the file to a transfer or storage service and paste the share link into the message. Three options worth knowing:
Filemail says free transfers have a maximum of 5 GB per transfer, with files available for 30 days (as of Nov 2026). Handy for one-off deliveries to a client.
Dropbox says you can share a link with anyone, even someone without a Dropbox account, and lists transfer limits of 50 GB and 100 GB depending on the plan.
Smash says it supports sending files over 100GB, which covers raw video and big design archives.
If file handling keeps getting in the way of how your team works, my roundup of other team chat apps is worth a read.
Finding, organising and deleting shared files
Once files are in, you'll find them through the Files tab, the Files & links tab in each channel, or search. Organising files into sidebar sections and creating external links to share files outside the app are limited to workspaces on a plan above Free.
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On deleting: any member or guest can delete a file they uploaded. Owners and Admins can delete files in public channels, and in private channels or DMs they belong to. If you're bringing a freelancer in as a guest, this guide on adding someone to a channel covers the access side.
My verdict on working inside the 1GB cap
For everyday documents, images and short clips, you'll rarely notice the cap. For video, raw design files or anything you'll want in six months' time, I'd keep the master in cloud storage and drop the link in the channel. It's faster for everyone, it doesn't depend on admin settings, and the file lives somewhere you control.
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Frequently asked questions
What's the biggest file I can upload to Slack?
Members and guests can add files up to 1GB.
How many files can I send in one message?
You can drag and drop up to 10 files at once.
Why does my file have no preview?
Images need to be under 25,000 pixels on the longest side and under 45 million pixels in total, and Office files over 50 MB show no preview.
Why is my upload blocked?
Slack Connect and Frontline Member restrictions, certain file types, or a malware scan can stop it.
What if my file is over 1GB?
Send a share link from a file transfer service and paste it into the message.
