Email attachment and upload size limits (Gmail, Outlook, Discord, WhatsApp)

There is no single email attachment size limit: each service sets its own. A personal Gmail account takes 25 MB of attachments per email, Outlook.com takes 25 MB per email including the text, and the Outlook desktop app stops at 20 MB by default for an IMAP or POP account. At work, your administrator sets the limit.

Chat apps set their own limits too. A free Discord account can upload 20 MB per file, WhatsApp sends documents of up to 2 GB, Slack takes files of up to 1 GB, and Telegram files of up to 2 GB, or 4 GB with Premium. We checked every figure below on the service's own help page on 22 October 2026, Telegram's on 25 October, and each one links to that page.

File size limits by service

Email attachment size limits in Gmail and Outlook

Gmail attachment size limit

Gmail Help's page on sending attachments gives the limit for a personal Gmail account as 25 MB, and it is a total: three 10 MB files will not fit in one email. For work and school accounts, the Google Workspace administrator sets both the sending and the receiving limit, so they are the people to ask.

Go over it and Gmail does not refuse the email: it takes the attachment out and puts a Google Drive link in its place. The person you write to gets a link to open rather than a file, which suits sharing but not an office that needs the file itself.

Outlook attachment size limit

Outlook has three limits, depending on which Outlook you use and the account behind it:

• Outlook.com, the free webmail: 25 MB per email, and that counts the text and any inserted pictures as well as the attachments, according to Microsoft's page on attaching files in Outlook.com. A OneDrive link does not count towards it and can point to a file of up to 2 GB.
• The Outlook desktop app with an IMAP or POP account: 20 MB of attachments by default, in Outlook 2013 and later. Over that, Outlook says the file is bigger than the server allows and suggests sending a link instead, as Microsoft's article on the attachment size error explains.
• A Microsoft 365 work or school account: 35 MB to send and 36 MB to receive by default. An administrator can set anything from 1 MB to 150 MB, says Microsoft's page on Exchange Online limits, and a message over the limit is not delivered: you get a non-delivery report instead.

Why a file just under the limit can still bounce

Email carries attachments as text, in an encoding called Base64 that turns every 3 bytes into 4 characters, as the email standard RFC 2045 sets out. On its way, a file grows by about a third.

Microsoft allows for this. Its Exchange Online limits page says a message that leaves its data centres grows by 33%, so Outlook on the web lets you send 25% less than the set limit: with a 100 MB limit, no more than 75 MB. Other services do not say whether they count a file before or after that growth, so leave a margin of a few MB under any email limit.

Upload limits in Discord, WhatsApp, Slack and Telegram

Discord upload limit

Discord's File Attachments FAQ gives the Discord upload limit as 20 MB for accounts without Nitro, up from 10 MB in August 2026. Nitro Basic raises it to 50 MB and Nitro to as much as 1 GB. Discord also says it is trying other limits with some users, so the number your own app shows is the one that counts.

Discord now checks a file's size before it compresses anything, on phones as well as computers. Its FAQ warns that on Android, where files tend to be larger, you may hit the limit more often than before, even though the number went up. For a clip that is too big, compress a video for Discord: the page opens at 8 MB, well under the free limit, and you can drag the target up towards 19 MB for a sharper picture.

WhatsApp file size limit

WhatsApp's help page on sending media sets two limits. Documents can be up to 2 GB. Videos have a default limit of 100 MB at 720p on a faster internet connection and 64 MB at 480p on a slower one, and on Android and iOS the page adds that media is usually compressed when shared, so it can arrive looking worse than the original.

Shrinking a video yourself first means you decide how small it gets, and a smaller file is quicker to send on mobile data. Compress a video for WhatsApp aims for about 60 MB, under both video limits, and you can move the target up or down.

Slack file size limit

Slack's help page on adding files says members and guests can add files of up to 1 GB, and on a computer you can drag up to 10 files into a message at once. Uploads may be restricted in Slack Connect conversations and for Frontline Members, and certain file types cannot be added at all; if that stops you, ask a workspace owner or admin.

Telegram file size limit

Telegram's FAQ says you can send and receive files of any type, up to 2 GB each, or 4 GB with Telegram Premium. Its Premium FAQ lists 4 GB file uploads among the paid features and adds that anyone can download the larger files a Premium user sends, so only the sender needs the subscription. Neither page says what happens to a file over the limit.

How to get a file under a size limit

The way down depends on the kind of file. Each of these tools shows the new size before you save, so you can check it against the limit you are aiming for.

Compress a video

Compress a video for email opens with a 20 MB target, a few MB under the 25 MB limit of Gmail and Outlook.com. It runs in your browser, so the video is never uploaded. The target is approximate, and the result lands near 20 MB rather than on it. Trim the start and end first: at the same size, a shorter clip keeps more detail. Posting to TikTok, Instagram, YouTube or X instead? Their upload limits are in our guide to social media video sizes and length limits.

Compress a picture

To compress an image, choose a quality or a Target size in KB, where a KB is 1,000 bytes. It runs in your browser too. With Allow a smaller picture size switched on, as it is to begin with, the picture is also made smaller in pixels when even the lowest quality is still too big.

Reduce a PDF's size

To reduce a PDF's size, Compress PDF offers three levels (Low, Recommended and High) or a Target size in KB. It makes the pictures inside smaller and keeps every page, its text and its fonts. In our test, a 3.4 MB PDF of three pages of photos came down to 237 KB with a 500 KB target. If a target is out of reach, you get the smallest version it can make, with a note saying how big it is.

Unlike the video and image tools, Compress PDF works on our servers: the PDF is uploaded, and it is deleted with its compressed copy after 24 hours. The free plan takes PDFs of up to 25 MB, 3 files a day, conversions included. If a PDF barely shrinks, our guide to why PDFs get big explains what is taking the space.

Or send a link instead

When a file has to stay large, a link gets round the limit. Gmail does this for you by switching to a Google Drive link, and Outlook.com can attach a OneDrive link to a file of up to 2 GB. Compressing is the better choice when the person needs the file itself in their inbox.

File size limit questions