# How to send large files by email on a Mac

An email attachment limit is measured after the file has been encoded for the trip, so a 25 MB limit holds about 18 MB of files - and past that you either send a link or send a smaller file.

- URL: https://swiftfox.studio/blog/send-large-files-by-email-on-mac
- Covers: https://swiftfox.studio/apps/sculpt, https://swiftfox.studio/apps/sweep
- Published: 2026-10-26
- Updated: 2026-10-26
- Publisher: Swiftfox Studio (https://swiftfox.studio)

## In short

- Attachments are base64-encoded before they travel, which adds about a third, so Gmail's and Yahoo's 25 MB holds roughly 18 MB of files and iCloud's 20 MB roughly 14 MB.
- Mail Drop in Apple Mail sends up to 5 GB as a download link that lasts 30 days, and it works from Gmail and Outlook accounts too, not only iCloud.
- Zipping turns many files into one attachment, but JPEG, HEIC, MP4 and most PDFs are already compressed and come out of a ZIP barely smaller.
- Shrinking the files is the only option that keeps the attachment an attachment, with nothing to download and nothing that expires.

## The real limit is about a quarter below the advertised one

Every mail service publishes a size limit, and every one of them is measured on
the message as it travels, not on the file you see in Finder. That difference is
the reason a 22 MB attachment bounces off a 25 MB limit.

Email was built to carry text. To send a photo or a PDF, the mail app first
rewrites it as base64, a text encoding that turns every 3 bytes into 4
characters. That alone makes an attachment about 33% larger, and the line breaks
added every 76 characters, the headers and the message itself take a little
more. Divide the limit by roughly 1.37 and you have what actually fits.

| Service | Advertised limit | Files that fit | Above the limit |
| --- | --- | --- | --- |
| Gmail | 25 MB | about 18 MB | Gmail swaps the file for a Google Drive link |
| Outlook.com | 25 MB | about 18 MB | OneDrive links up to 2 GB do not count |
| Classic Outlook, IMAP or POP account | 20 MB by default | about 14 MB | Outlook refuses the attachment |
| Microsoft 365 work account | Set by your admin | Ask, then take a quarter off | Depends on the organisation |
| iCloud Mail | 20 MB | about 14 MB | Mail Drop, up to 5 GB |
| Yahoo Mail | 25 MB, all attachments combined | about 18 MB | Send a cloud link |

One more catch: the limit that counts is the smaller of yours and the
recipient's. A 17 MB attachment leaves Gmail fine and bounces off a company
server set to 10 MB, and there is no way to know that from your side.

## Five ways round it, side by side

| Option | Best for | Size | What the recipient gets | The catch |
| --- | --- | --- | --- | --- |
| Mail Drop | Anything up to 5 GB, from Apple Mail | 5 GB | A download link | Expires after 30 days |
| Cloud share link | Big files, files that must stay available | Your storage | A link to your Drive, OneDrive or iCloud Drive | Uses your storage, needs a click and sometimes a sign-in |
| WeTransfer and similar | A one-off large file to anyone | 3 GB per 30 days free | A download link | Free links last 3 days |
| ZIP | Many files as one attachment | Barely smaller for photos, video, PDF | One archive | Rarely gets you under the limit |
| Smaller files | Photos, PDFs, short clips | Under the real limit | Real attachments | Video loses detail when squeezed hard |

The first three stop sending the file and start sending a link. That is the
right trade for a 2 GB video and the wrong one for six photos of a flat, a
signed contract or a form that has to arrive as an attachment, where a link is
one more thing to click, expire or get blocked by a company mail filter.

## Mail Drop wins if you already use Apple Mail

Mail Drop is built into Mail on the Mac. When a message is over the limit, Mail
uploads the attachments to iCloud and sends a link instead, up to 5 GB per
message. The link expires after 30 days, and the files do not count against
your iCloud storage.

It is not only for iCloud addresses. From a Gmail, Outlook or work account, Mail
asks whether to use Mail Drop when a message is too big, as long as you are
signed in to your Apple Account. You can turn it on per account in Mail,
Settings, Accounts, under "Send large attachments with Mail Drop". The person
receiving it can use any mail app.

Where it loses: the files vanish after 30 days, so it is wrong for anything the
recipient needs to keep, and it does nothing if you write mail in a browser or
in Outlook.

## A share link wins when the file is huge or has to stay put

Put the file in Google Drive, OneDrive or iCloud Drive and send the link. Gmail
does this for you above 25 MB: it takes the file out and inserts a Drive link.
Outlook.com does the same with OneDrive, for files up to 2 GB.

This is the right answer for a long video, a folder of raw photos or a document
you will keep updating, because the link stays alive for as long as you leave
the file shared. The costs are real but small: it counts against your storage
(the free tiers are 15 GB at Google, 5 GB at Microsoft and 5 GB at iCloud), the
recipient may have to sign in or request access, and some company filters strip
cloud links from incoming mail.

## WeTransfer wins for a one-off to a stranger

Services like WeTransfer upload the file to their servers and email a link.
Nobody needs an account, which is the whole appeal when you send a large file
once to someone you do not share a cloud with.

The free plan is now tighter than its reputation: 10 transfers or 3 GB in any
30-day window, and each link lasts 3 days. Fine for a one-off, poor for a
recipient who opens their email on Monday about a link you sent on Thursday.
The files also sit on a third party's server for those days, which matters for
contracts and medical records.

## Zipping bundles files, but rarely shrinks them

Select the files in Finder, right-click and choose Compress. You get one
archive, which is the real benefit: one attachment instead of forty, folders
kept intact, nothing lost on the way.

What it does not do is make most attachments smaller. ZIP removes repetition,
and JPEG, HEIC, PNG, MP4, MOV and most PDFs have already had their repetition
removed by their own compression. A ZIP of holiday photos usually comes out
within a few percent of the originals. It does shrink text, spreadsheets,
uncompressed TIFF and WAV, sometimes by half or more. So zip to tidy a batch,
not to get under a limit.

## Smaller files are the only way the attachment stays an attachment

If the recipient should get the files themselves, with nothing to download and
nothing that expires, the files have to be smaller. Your Mac already does some
of this for free:

- **Mail's image size menu.** Add photos to a message in Mail and a size menu
  appears in the header: Small, Medium, Large or Actual Size. Quick, but it
  only does photos and you are guessing at the total.
- **Preview.** File, Export, then Quartz Filter, Reduce File Size. It shrinks a
  PDF hard, often too hard: scanned pages can turn blurry enough to be
  unreadable.
- **QuickTime Player.** File, Export As, and a lower resolution such as 720p.
  It gets a clip smaller, but you cannot ask for a size, so you try until it
  fits.

None of the three knows the limit you are aiming at. That is the gap
[Sculpt](https://swiftfox.studio/apps/sculpt) was built for.

## What Sculpt does with the email limit

Sculpt is our offline file converter for images, PDFs, video and audio. You
drop files on its window or its Dock icon, paste them with ⌘V, or right-click
them in Finder, and nothing is uploaded anywhere. Three of its built-in
presets are about getting files into an email.

**Email attachment** turns photos into JPEGs that fit Gmail's real limit
together. The target is 18 MB for the whole batch, not per photo, because an
email has one limit and not one per attachment: drop twelve photos and Sculpt
splits the 18 MB between them by size. Location data is removed on the way.

**Video for sending** brings each clip to 14 MB, at most 1280 pixels on the long
edge and 30 frames a second, as an H.264 MP4. Here each clip gets the whole
target, because videos go one per message; splitting it between ten clips would
leave each too blurred to watch. 14 MB is the tightest of the limits the app
knows, so the same file also fits iCloud Mail and WhatsApp.

**Shrink PDF** recompresses the pictures inside a PDF and keeps the text
selectable, the links and the bookmarks, with four strengths from Screen to
Archive.

The targets are already net of base64. The size picker offers Gmail at 18 MB
and Outlook and iCloud at 14 MB; on screen they read 18.9 MB and 14.7 MB,
because Sculpt counts megabytes the way Finder does. The 14 MB choice is built
for 20 MB services like iCloud and classic Outlook. Outlook.com on the web now
takes 25 MB, so Gmail's 18 MB fits there too.

![Sculpt's settings for one output, with a size target chosen so the converted files fit inside an email](https://swiftfox.studio/blog/send-large-files-by-email-on-mac/fig-1.jpg "The size target is what the email can actually carry, with the encoding already taken off.")

Any output can also be set to **deliver as one ZIP**, which packs its files into
a single archive ready to attach. That is the useful half of zipping, the one
attachment, on top of files that are already small enough. Originals are kept,
and every batch can be undone in one click.

![A finished Sculpt run listing each converted file with how much smaller it got, with Undo and Show in Finder buttons](https://swiftfox.studio/blog/send-large-files-by-email-on-mac/fig-2.jpg "Each row shows what the file weighs now. Undo puts the whole batch back.")

Where Sculpt does not win: it cannot make a 2 GB video fit in an email at a
quality worth watching, and it does not send anything itself. For those, use a
share link or Mail Drop. Sculpt is $13.99 once, with a 30-day free trial, on
macOS 14 or later. If you want a step-by-step guide to converting many files at
once, see [batch converting files on a Mac](https://swiftfox.studio/handbook/batch-convert-files-on-mac).

## Which one to use

- **A few photos or a PDF** for someone who should just get the files: shrink
  them, then attach.
- **One large video**: a share link, or Mail Drop if you write in Apple Mail.
- **A big folder for a stranger, once**: WeTransfer, before the 3 days run out.
- **Forty small files**: ZIP them, for the tidiness, not the size.

The big files you send and receive tend to stay on the disk long after the
email has gone. [Sweep](https://swiftfox.studio/apps/sweep) can file what lands in Downloads and list
the large files nobody has opened in months, and
[freeing up disk space on a Mac](https://swiftfox.studio/blog/free-up-disk-space-on-mac) covers the
rest.

_Prices and features checked on 26 October 2026._

## Frequently asked questions

### Why did a 22 MB attachment bounce when Gmail's limit is 25 MB?

Because the limit applies to the message as it travels, not to the file in Finder. Email can only carry text, so every attachment is base64-encoded first, which makes it about a third larger, plus line breaks and headers. A 22 MB file becomes roughly 30 MB on the wire. Keep the files under about 18 MB in total for a 25 MB limit.

### Does Mail Drop work with a Gmail or Outlook account?

Yes, from Apple Mail on the Mac, as long as you are signed in to your Apple Account. For an account that is not iCloud, Mail asks whether to use Mail Drop when a message is too big, and you can tell it to stop asking. The recipient can use any email app; they get a download link instead of the file.

### Does zipping make files smaller for email?

Only some files. Text, spreadsheets, uncompressed TIFF and WAV can shrink a lot. JPEG, HEIC, PNG, MP4, MOV and most PDFs are compressed already, so a ZIP of them is usually within a few percent of the original. Zip to send one attachment instead of forty, not to get under a limit.

### How long do the download links last?

Mail Drop links expire after 30 days. A free WeTransfer link lasts 3 days. A Google Drive, OneDrive or iCloud Drive link lasts until you stop sharing the file or delete it, which is the better choice for something the recipient needs to keep.

### Will shrinking a photo or a video to fit ruin it?

Not at email sizes, as a rule. Most phone photos are larger than any screen they will be viewed on, so a JPEG at a sensible size looks the same. Video is where it shows: a long clip squeezed to 14 MB loses detail, and for that a share link is the honest answer.

### What do these options cost?

Mail Drop, Finder's Compress and the free tiers of Google Drive, OneDrive and iCloud Drive cost nothing. WeTransfer's free plan allows 10 transfers or 3 GB in any 30 days. Sculpt is $13.99 once, with a 30-day free trial, and runs on macOS 14 or later.