Email Attachment Size Limits: Gmail, Outlook, Yahoo, iCloud

Quick Answer

For personal accounts, the published limits are 25 MB for Gmail and Yahoo Mail, 20 MB for iCloud Mail, and 20 or 25 MB for Outlook.com. A message is only as big as the lowest limit between the sender and the receiver, so mail to an iCloud address is held to 20 MB whoever sends it.

We read each provider's own help page on 6 November 2026 and sent no test messages, so these are the published figures, not measured ones. Where a page gives no number we print "Not published" and leave it there.

Chart

This table covers personal accounts. Work and school accounts follow an administrator, and they are in the next section.

Where each figure comes from:

• Gmail. Google's page on sending attachments says "For personal Gmail accounts, the limit is 25 MB." It gives no receiving figure. The page prints no date.
• Outlook.com. Microsoft's guide to reducing attachment size gives 20 MB for internet email accounts such as Outlook.com or Gmail, in a page about the Outlook app. Its page on Outlook.com sending limits says 25 MB for a file. Neither page gives a receiving figure and neither prints a date, so we print both sending numbers.
• Yahoo Mail. Yahoo's message size page says the sum of all attached files in one message, "both for incoming and outgoing email", must not exceed 25MB. It prints no date.
• iCloud Mail. Apple's mailbox and message limits page, published March 17, 2025, lists the size of incoming and outgoing messages as 20MB, up to 5GB with Mail Drop turned on.

In the Pairs table, Outlook means Outlook.com, and the pages do not count the same thing. Yahoo counts the sum of the attached files, Microsoft says its limit includes "both the size of the attachment and the size of the email", and Apple says "incoming and outgoing messages". We cannot say from the pages which is stricter in practice.

Work

Work and school accounts have their own numbers, and most of them are set by an administrator. Google Education has the same figures as Google Business, and the Exchange figures are defaults. Our posts on the Gmail attachment size limit and the Outlook attachment size limit cover editions and admin settings, so this is only the chart.

Google's sending-limits page, Gmail sending limits in Workspace, lists "Up to 50 MB" for Enterprise Plus and 25 MB for Enterprise Standard, and marks the 50 MB as available only on the web version of Gmail. Its receiving-limits page gives 50 MB for Enterprise Standard and 70 MB for Enterprise Plus, while its editions table gives 35 MB and 35 to 50 MB. The two pages disagree, so the table shows the range. All three pages say "Last updated 2026-10-26 UTC".

Microsoft's Exchange Online limits, dated 19 October 2026, give a default of 35 MB for sending and 36 MB for receiving, and let an administrator choose between 1 MB and 150 MB. The 10 MB is the "default email size limit" for "Exchange accounts (business email)" on Microsoft's attachment guide, which words it as one limit and does not split it into send and receive. We put it in the Send column as the nearest fit, and it is Outlook's limit, not a server setting we read.

Pairs

A message crosses two sets of rules, so the number to plan around is the lowest published figure for the pair. This table is our reading of the charts above, not a statement from any vendor.

Where a receiving limit is "Not published", the pair figure is the sending side's number, and a lower limit on the receiving side is possible. Apple's Mail Drop page says as much about its own links: "The recipient's email app might have a smaller message size limit that prevents the attachment from being delivered." iCloud Mail's 20 MB is the lowest figure published for any of the four, and Microsoft's guide gives the same 20 MB for internet accounts such as Outlook.com.

Growth

A file takes up more room in an email than it does on your Mac, because email carries attachments as text. Microsoft says messages routed outside its datacenters get "an additional 33% translation encoding increase" on its Exchange Online page. Google says its Workspace receiving limits are "the limit after encoding, which adds about a 37% increase" on its receiving-limits page. Both can be right, and neither vendor explains why.

Our arithmetic, not either vendor's: the email standard, RFC 2045 of November 1996, says Base64 turns a 24-bit group of input into 4 encoded characters, so 3 bytes become 4, and a growth of 4/3, about 33%. It also says the encoded output must be in lines of no more than 76 characters. Each line then carries a 2-character line break, which adds 78/76 more, and 4/3 times 78/76 is about 1.368, the 37%. That fits both figures as one effect counted at two levels of detail, though neither vendor says so.

Here is how much file fits under each limit if the limit is counted after encoding. Google's receiving page says its 50 MB for Enterprise Standard is counted that way, and Microsoft's page does not say for its 35 MB. We divided each limit by 1.368 and by 1.333.

Whether the figure is counted before or after encoding changes the answer, and the pages differ. Google's Workspace sending page says its figures are limits on the total size "before encoding", and its receiving page says "after encoding". Yahoo's page says "25MB in total file size", which may mean the files' own size, but it does not say whether that is before or after encoding. Apple's 20MB and Google's personal 25 MB are not stated either way. If those are counted before encoding, the full number is usable. If they are counted after, the table is the safe margin. A file of about 14 MB is the size that passes a 20 MB limit under either reading, because 14 times 1.368 is about 19.2.

File Types

Size is not the only thing that stops a file. Three of the four providers publish a list of blocked types. Google says Gmail also checks types inside archives, while Microsoft's page says a compressed archive is not blocked by Outlook and Yahoo's pages say nothing about zips, so a zip is not a rule-proof way round.

Google's blocked types page lists .dmg, .iso and .img among others, says the list changes often, and also blocks certain types found inside archives and "Password-protected archives with archived content". Microsoft's blocked attachments page lists .app, .img and .iso, and we did not find .dmg on it. Yahoo's attach page gives ten examples with "such as": .bat, .cmd, .exe, .hta, .iso, .jar, .lnk, .msi, .scr and .vbs. Apple's Mail Drop page says "All files types are supported", and we found no Apple page listing blocked types for iCloud Mail.

Not named on a page is not the same as allowed, and we sent no .dmg through Outlook or Yahoo, so we do not say it goes through.

Links

Each provider offers a way to send a file over its limit as a link, though for Yahoo only its AT&T page says so.

Google says Gmail "automatically removes the attachment and adds it as a Google Drive link" when the total is over the limit, and its Drive file limits say "All other files" go up to 5 TB, which is Drive's limit, not Gmail's. Microsoft's Outlook.com page says the attachment size limit for OneDrive files is 2GB. Apple's Mail Drop page says attachments up to 5 GB, with recipients getting 30 days to download.

For Yahoo, the only page we found that tells people to use a cloud link is its page for AT&T Yahoo Mail, which says to "use the option to share files from Google Drive or Dropbox" for a file over 25MB. The standard Yahoo pages we read do not say it, so we could not confirm the option for an ordinary Yahoo Mail account.

Our post on Mail Drop on Mac has the steps for Apple's route, and the guide to sending large files through email helps choose a route by file size.

Loop

Loop is a Mac app by Theodore HQ that turns a file into a link stored in your own Cloudflare account. You paste the link into your email, so the message carries a line of text instead of the file. It does not raise a limit, and for one file sent once, the link your provider makes, whether Drive, OneDrive or Mail Drop, is simpler.

Loop costs $49 once, runs on macOS 14 or later and needs a Cloudflare account. We do not promise a maximum file size. Your Mac shows a notification the first time each reader's web browser opens a link, while Loop is running.

Limits

Loop is not the answer to most of the questions on this page. It does not:

• Change what an email service accepts. It does not replace the link your provider makes, and a Loop link is just text in your message.
• Send the email. You copy the link and paste it into the message.
• Shrink, zip or encrypt a file. A link password does not encrypt the file.
• Promise to get past a blocked type. We have not tested how any of these providers treat a link to a .dmg or .iso.
• Send an alert by email or phone. Alerts are Mac notifications while Loop runs: opens and downloads once per reader's web browser per link, and notes, questions and signatures each separately.
• Work from an iPhone or Windows. The sender needs a Mac, and readers open the link in a web browser.

Cost

We did not price Drive, OneDrive or Dropbox here, and the Gmail and Outlook posts cover them. Apple's Mail Drop page says attachments do not count against your iCloud storage. Loop is $49, paid once.

Loop keeps files in your Cloudflare account, which includes 10 GB-month of storage a month at no charge. After that Cloudflare bills you, and its R2 pricing page, last updated 30 October 2026, lists standard storage at $0.015 per GB-month and egress to the internet as free. Storing 100 GB for a month would cost about $1.35 after the free 10 GB. Loop's own setup says Cloudflare may ask for a card when you turn storage on.

A 14-day free trial starts the first time you run Loop and takes no payment. During the trial a small "Shared with Loop" badge shows on the pages readers see, and a licence removes it.