If Gmail won't attach or send your file, a full Google storage quota is as likely a cause as an oversized file — and Google says so in plain language. From Gmail's own help page on attachments: "Attachments count toward your Google storage. Storage is shared across Drive, Photos, and Gmail. If you reach your storage limit, you can't send or receive attachments."
That sentence is the whole article in miniature. Most troubleshooting advice for this problem starts with shrinking the video, which is the right move for a different failure. If your quota is full, a 4 MB clip fails just as reliably as a 400 MB one.
What "storage full" actually blocks
Two official pages describe the consequence, and they are worth reading side by side because their scope is not identical.
Gmail's attachment page, quoted above, limits the statement to attachments: you "can't send or receive attachments."
Google Drive's storage management page states it more broadly: "When your account reaches its storage limit, you won't be able to upload or create files in Drive, send or receive emails in Gmail, or back up photos or videos to Google Photos."
The common ground is what matters: one quota, three products. Google's page on buying more storage says a Google Account "comes with up to 15 GB of cloud storage at no charge" and that storage is shared across Google Drive, Gmail and Google Photos. So the 200 photo backups and the shared folder someone dumped on you are competing for the same pool as your outbox.
The practical consequence: a Gmail attachment failure can be caused by something you did in an entirely different product, on an entirely different day.
Why "file too big" and "storage full" look identical — but aren't
Here is the detail that separates the two failures, and it is the reason storage gets misdiagnosed as size.
Going over Gmail's size limit does not produce a refusal. Gmail's help page describes what happens instead: "If your total attachment size is greater than the limit, Gmail automatically removes the attachment and adds it as a Google Drive link in the email."
So the oversized-file path is not a dead end — it is a redirect. The file stops being an email attachment and becomes a Drive link. Two things follow from that, both documented:
- The redirect requires Drive to be writable. If your quota is full, Drive's page says you can't upload or create files there either. The fallback route is closed at the same time as the main one.
- Either way, it counts. Attachments count toward your Google storage, per the Gmail page. Sending the file does not get it off your books.
Worth knowing while you diagnose: for personal Gmail accounts, Google states the limit is 25 MB, and it applies to "your total attachment size" — not per file. Three 10 MB clips in one message is a 30 MB message. For work and school accounts, Google says your Google Workspace administrator sets the attachment sending and receiving limits, so the number on your account may differ. The full breakdown lives in Gmail's attachment size limit for video.
The fastest fix
There are only two levers, and they work at different speeds.
Lever one: make room in the quota. Either free space across Drive, Gmail and Photos, or add storage. Google lists Google One as starting with 100 GB, and Google Workspace Individual as coming with 1 TB. For the actual steps of finding and clearing what is using your space, check the official documentation — Google's storage management page is the place to do it, and the specifics change.
Lever two: stop feeding the quota. Since attachments count toward the same shared pool, the size of what you send is also the size of what it costs you. A phone or screen-recorder video is routinely many times larger than it needs to be for something that will be watched once in an email client. Getting a clip comfortably under Gmail's stated personal limit keeps it a plain attachment instead of pushing it down the Drive-link path — and a smaller file is a smaller claim on the 15 GB.
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
This runs inside your browser tab. The video is read from disk, re-encoded locally and handed back — it is never uploaded anywhere, so it doesn't touch your Google storage on the way to fixing your Google storage problem. If your source is a QuickTime file off a Mac or iPhone, MOV to MP4 does the container conversion in the same place.
Other causes, in order of likelihood
Storage and size account for most of these failures. When neither applies, Google documents several others.
The upload hasn't finished. Gmail's page is blunt about this one: "If you upload files from another device, wait until the upload completes. Then send the attachments in your current message."
The browser is the problem. For attachments that won't upload on desktop, Gmail's help page lists exactly three checks:
Make sure you're using a supported browser.
Try adding the attachment in another browser.
If you've set up a web browser proxy, try disabling it.The file type is blocked. To prevent viruses, Gmail doesn't let you attach executable files, like files ending in .exe. The published blocklist also includes .img and .iso, which means a disc-image copy of footage is refused regardless of size or quota. Two things to note: no common video or audio extension appears on that list, and Google warns that "Gmail often updates the types of files not allowed to keep up with harmful software that is constantly changing" — so verify against the live page rather than a copy of it.
The attachment host is blocked on your network. Gmail's page names the cause directly: "Your network administrator or Internet provider probably blocked "mail-attachment.googleusercontent.com," the domain Google uses to host attachments."
You hit a sending limit that has nothing to do with files. Gmail's limits page: "You may see this message if you send an email to a total of more than 500 recipients in a single email and or more than 500 emails sent in a day." It adds that "When you get this error, you should be able to send emails again within 1 to 24 hours." More cases like this one are collected in the fix archive.
How to tell it worked
Check your storage figure first — that is the number that gates everything above. Then send a test message to yourself with the file attached.
The tell is what the message looks like after it sends. If the file arrives as an attachment, you are inside both the quota and the size limit. If it arrives as a Drive link, Gmail applied the swap described above, and from that point access is governed by Drive sharing rather than by email. Google notes that when you attach a Drive file, "Gmail checks to see if your recipients have access to the file. If they don't, you'll be prompted to change the sharing settings of the file before you send your message."
FAQ
Why can't I send attachments in Gmail when my file is small? Because size is not the only gate. Google states that attachments count toward your Google storage, that storage is shared across Drive, Photos and Gmail, and that if you reach your storage limit you can't send or receive attachments. A small file fails too.
Do Gmail attachments use up my Google Drive storage? They use the same shared pool. Google's wording is that attachments count toward your Google storage and that storage is shared across Drive, Photos and Gmail — one quota, not three separate ones.
What happens if my attachment is over Gmail's size limit? Google says Gmail automatically removes the attachment and adds it as a Google Drive link in the email. It is a conversion, not a rejection — but it needs room in Drive, which a full quota denies you.
Does Gmail compress video attachments to fit? Google's Gmail help pages make no statement that Gmail transcodes or compresses attachments, so don't plan around it. Shrink the file yourself before attaching it; the browser-based compressor above and the rest of the Clapr tools all run locally.
How much free storage does a Google Account include? Google states a Google Account comes with up to 15 GB of cloud storage at no charge, shared across Drive, Gmail and Photos. Paid options it lists include Google One, starting with 100 GB, and Google Workspace Individual, with 1 TB.
Quotes taken from Google's official Gmail and Drive help pages, checked 16 September 2026. Google changes these pages without notice — verify current limits against the official documentation before relying on them.
