Asana's documented file attachment size limit is 100MB, and it's enforced when a file is uploaded through the attachments endpoint. For anything bigger, host the file on Dropbox, Google Drive or OneDrive and attach it to the task as a link instead of uploading the file itself.
When a design file or video refuses to upload
You've got a client video, a print-ready PDF or a zipped folder of brand assets, and you want it sitting on the task where everyone can find it. Then the upload stalls. Nine times out of ten the reason is simple: the file is over the size cap, and no amount of retrying will push it through.
The good news is that the cap only applies to files you upload into the task. Links to files stored somewhere else don't count against it, and that's the route I'd point you to for anything heavy.
The 100MB cap and the other attachment rules
Here's what the developer documentation sets out. The table covers the size cap itself and the rules that decide how a file can be attached.
| Item | Limit | Applies to |
|---|---|---|
| Maximum attachment size | 100MB | File uploads through the attachments endpoint |
| Upload format | multipart/form-data with the full file contents | The upload an attachment API call |
| External link attachment | Needs a parent, a name and a url | Attachments with the external subtype |
| Supported link hosts | asana, dropbox, gdrive, onedrive, box, vimeo, external | The attachment host field |
| Third-party file content via the API | Can't be attached directly | Dropbox, Box, Vimeo and Google Drive files |
So what happens when you hit 100MB? The upload endpoint is where the cap is enforced, so a file over it simply won't be accepted as an upload. There's no partial upload and no automatic compression. You either shrink the file, split it, or attach it as a link.
It's worth knowing what an attachment is in the first place. The docs describe an attachment object as any file attached to a task, whether it was uploaded or associated through a third-party service such as Dropbox or Google Drive. That's why a linked file still shows up on the task like any other attachment, and your team doesn't have to hunt for it.
Getting a large file onto a task without uploading it
This is the workaround I'd use for any file you already know is big.
- Upload the file to a cloud service you already use, such as Dropbox, Google Drive, OneDrive or Box.
- Check the sharing settings so the people on the task can open it.
- Copy the share link and attach it to the task as a link rather than a file.
- Give it a clear name, so the task shows what the file is at a glance.
If you're building an integration or a script, the same idea applies. An external attachment needs three things: a parent (the task), a name and a url. The host field accepts asana, dropbox, gdrive, onedrive, box, vimeo and external.
A few technical points from the documentation if you upload through code. Uploads expect a multipart/form-data request containing the full contents of the file. For PDFs sent with curl, force the content type to PDF, and pass file names with non-ASCII characters encoded in the Content-Disposition header. Once a file is attached, the record can return size, download_url, permanent_url and view_url fields, which is handy if you want to check what went through.
Why a Drive or Dropbox file can't be pulled straight in
This trips people up. According to the Asana developer documentation, you can't attach files from Dropbox, Box, Vimeo or Google Drive through the API by their file content. You have to download the file first and upload it again, or attach it as an external link. If the file is over 100MB, the link is your only route.
One more honest note. The 100MB number comes from the developer documentation for the upload endpoint. I couldn't confirm a separate number for uploads made in the app itself, and I'm not going to invent one, so if you're right on the edge, check it in the app before you promise a client anything.
How other work apps handle file size
Trello states a 10 MB upload limit per attachment, with a larger 250 MB limit on upgraded accounts. That's a much lower starting point if your team lives on boards.
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Notion says that on its free plan all uploaded files must be under 5MB (as of Nov 2026). Fine for screenshots and short documents, not for video.
If file handling is a deal breaker for your team, my roundup of other project tools worth a look covers the wider options, and the guide to choosing project management software helps you weigh file limits against everything else.
My advice if you only do one thing
Stop uploading big files into tasks at all. Keep the master copy in one cloud folder, attach the link, and name it well. You'll never hit the 100MB wall, your team always opens the latest version, and nobody ends up with five copies of the same video scattered across a project.
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Frequently asked questions
What's the maximum file size you can attach in Asana?
The developer docs state a 100MB limit on attachments, enforced on the upload endpoint.
How do I share a file larger than the limit?
Attach it as a link to a file hosted elsewhere. External attachments need a parent, a name and a url.
Which cloud services can attachments point to?
The docs list asana, dropbox, gdrive, onedrive, box, vimeo and external.
Can I upload through the API?
Yes, with a multipart/form-data request containing the full file contents.
How does it compare to Trello on attachment size?
Trello states 10 MB per attachment, with a larger limit on upgraded accounts, so the 100MB documented limit is higher than Trello's base limit.
