Most email providers stop accepting attachments at 20 to 25 MB, and the real ceiling is lower than the number printed in the help page. Two fixes work for nearly every file. Make it smaller before you attach it, which usually means compressing or resizing the images inside it. If it has to stay at full size, send a link instead of the file. We built our browser tools for the first fix: they compress images, resize them and build PDFs on your own device, with no upload and no account.
TL;DR
- Gmail allows 25 MB per message for personal accounts, Outlook.com allows 25 MB, and Outlook with an internet email account allows 20 MB. Work accounts can be lower or higher.
- Encoding makes an attachment about 37% bigger in transit, so a file near the limit can still bounce. Aim for roughly 18 MB or less.
- Most oversized files are oversized because of photos or scans. Compress or resize the images and the file often drops under the limit.
- If a file must stay at full quality, upload it to cloud storage and email a link, with permissions set on purpose.
Table of Contents
- Why email turns your file away
- Step 1: Find out what you are actually sending
- Step 2: Shrink the images first
- Step 3: When the PDF is too large to email
- Step 4: Share a link when the file must stay whole
- Making a shared link safe
- Which fix to choose
- Try it on your own file
- Our view: fix the file before you fix the delivery
- FAQ
- Sources
Why email turns your file away
The limit is not one number. It depends on your provider, your account type and the account on the receiving end. Microsoft 365 says most email providers cap attachments at 20 to 25 MB, that the usable ceiling is near 18 MB because of encoding, and that the recipient's provider enforces its own limit too. A file that leaves your outbox can still be bounced or blocked on the other side.
Here is what the main providers publish.
| Account | Attachment or message limit | Source |
|---|---|---|
| Personal Gmail | 25 MB sending limit | Gmail Help |
| Gmail for work or school | Set by the Google Workspace administrator | Gmail Help |
| Outlook, internet email account | 20 MB | Microsoft Support |
| Outlook, Exchange business account | 10 MB by default, counting the attachment and the email together | Microsoft Support |
Two details trip people up. First, the Outlook limit applies to one attachment over 20 MB or to several attachments whose total goes over it, as Microsoft Learn explains. Five 5 MB photos are a 25 MB problem. Second, the cap covers the whole message, so the body text and any signature images count too.
The 37% problem
Email was designed for text. Attachments are converted into a text-safe format called base64, and SMTP.dev notes that this makes them about 37% larger than the original file. That is why a 24 MB PDF can fail a 25 MB limit. Divide the stated limit by 1.37 to find the largest file that fits: 25 MB becomes about 18 MB, and 20 MB becomes about 14.6 MB.
Microsoft also ties Outlook's limit to a practical reason: it stops your computer from repeatedly trying to upload huge attachments that exceed what most internet service providers accept. The limits are there for a reason, so the goal is to work within them.
Step 1: Find out what you are actually sending
Before you pick a fix, look at the size of the file and, more importantly, what is inside it.
- Check the file size. On Windows, right-click the file and choose Properties. On a Mac, select it and press Command-I. Add the sizes together if you are sending several files.
- Apply the 1.37 rule. If the total is over about 18 MB for Gmail or Outlook.com, or about 14 MB for an Outlook internet account, expect trouble.
- Ask what the file is made of. A 40 MB PDF is almost always a stack of phone photos or scans. A 30 MB set of attachments is usually a handful of unedited camera images. A video is a different case, covered below.
- Know the recipient's side. If they use a company mailbox, their limit may be lower than yours, and you will rarely see it until a bounce message arrives.
The point of this step is that it tells you whether shrinking is realistic. Photos and scans shrink well. Files that are already tight, such as a finished video, do not.
Step 2: Shrink the images first
When the weight comes from pictures, this is the quickest fix and the one that leaves the recipient with a normal attachment they can open without extra accounts or links.
A modern phone photo is often several megabytes, and a document or email rarely needs that resolution. There are two levers:
- Compression lowers the file size by re-encoding the image at a smaller size while keeping it looking the same on screen.
- Resizing reduces the pixel dimensions. A photo shown at 1,200 pixels wide in an email does not need 4,000.
Our image compressor handles JPG, PNG and WebP files in your browser. You drop the images in, and the processing happens on your device, so a photo of a signed contract or an ID never leaves your computer. There is no account to create and no software to install. If you need smaller dimensions as well, the same suite includes a resizer, and our guide on reducing an image toward a file-size limit walks through getting a picture under a specific number.
A workable routine:
- Compress every image you plan to attach.
- If the total is still over your target, resize the largest ones.
- Re-check the combined size with the 1.37 rule in mind.
- If you receive WebP images that your recipient cannot open, convert them to JPG with the WebP to JPG tool before attaching.
Where people go wrong is compressing one image and forgetting the other six, or shrinking an image that is then placed into a PDF at full size again. Do the compression before the document is assembled. Our post on an image that is too large to upload covers the same problem for web forms, and the method carries over to email.
Step 3: When the PDF is too large to email
A PDF is a container. Its size depends on what you put in it, and for most scanned or photo-based documents that means images.
If you are building the PDF from images, shrink the images first, then combine them. Compress the photos or scans with the image compressor, then use JPG to PDF to put them into one document. The PDF starts from lighter pages, so you are not trying to squeeze a finished 60 MB file afterward. Because the conversion runs locally in your browser, the pages are not sent to a server.
If you have several PDFs, you may not need one huge file at all. Splitting a package into logical parts, such as a signed contract in one message and exhibits in another, keeps each email under the limit. When the recipient wants a single document, merge the PDF files after you have trimmed each part, and check the final size before attaching it.
If the PDF came from a scan, the scan settings matter. StrongFolder's guide suggests scanning at 200 to 300 dpi in grayscale rather than 600 dpi in color when the document is text. That is often the difference between 5 MB and 50 MB.
If it is a print-quality file, do not shrink it. A designer's proof or a high-resolution brochure is large for a reason. Send those by link, as described next.
Zipping rarely helps with PDFs. Their images are normally already compressed, so a zip archive saves little, and it adds a step for the recipient. Splitting a file across several emails is possible but tedious, and the recipient has to rebuild it. Reducing the images is cleaner.
Step 4: Share a link when the file must stay whole
Some files should not be touched: raw video, design files, large datasets, long recordings. For those, the standard approach is to upload the file to cloud storage and email a link. Microsoft 365 describes this as saving the file to the cloud and sharing the link by email, chat or text, and says cloud links can carry files up to 250 GB.
Several email services do this for you:
- Gmail replaces attachments over the limit with a Google Drive link automatically, as Gmail Help states. Gmail also checks whether your recipients have access to a Drive file before the message goes out.
- Outlook.com offers OneDrive links for files up to 2 GB, according to Email Analytics.
- Zoho Mail has a Huge Attachment feature that sends a link, with size depending on the plan: 250 MB on Mail Lite, 500 MB on Workplace Basic and 1 GB on higher plans, according to Zoho's documentation.
The trade-off with a link is that the recipient depends on it: it can expire, it can be set to the wrong permission, and some company mail systems filter or distrust unfamiliar links. For a business recipient who has told you not to send links, shrinking the file to fit is the safer route, which is one more reason to try Step 2 first.
Videos need a note of their own. A personal Gmail account can attach a video only if the total attachments stay within 25 MB, and work accounts follow the administrator's setting. Most videos are far larger than that, so a video is a link case.
Making a shared link safe
A link is a door. Set who can walk through it.
- Name the people who may open the file rather than letting anyone with the link in, for anything sensitive. Microsoft 365 recommends this, along with view-only access where editing is not needed.
- Add an expiration date and a password for financial, legal or customer records. Microsoft 365 recommends both for those categories.
- Know how Drive sharing behaves. With "Anyone with the link" you choose whether people can view, comment or edit, and recipients do not need a Google Account to see the file.
- Know how to switch it off. Proton's documentation says a public link can have a password and an expiry date, and that once sharing is stopped, anyone using the link loses access immediately.
- Send the password separately from the link, for example by text message, so one intercepted email does not expose the file.
If the document includes a photo with location data, think about what it reveals before it goes anywhere. Our tool for removing JPEG EXIF data re-encodes the image so the embedded metadata is not carried along.
Which fix to choose
| Your file | Best first move |
|---|---|
| A handful of photos | Compress, then resize if needed, and attach |
| A PDF made from photos or scans | Compress the images, rebuild with JPG to PDF |
| Several PDFs | Trim each, merge, check the total size |
| Print-quality design or proof | Cloud link with a password and expiry |
| Video or large dataset | Cloud link |
| Sensitive documents | Shrink locally, then send by named-person link if still too big |
Try it on your own file
If your attachment is mostly photos or scans, you can fix it in a minute without installing anything. Our free browser tools include image compression, resizing, WebP to JPG, JPG to PDF and PDF merging. Files are processed locally in your browser, with no upload and no account. The data processing page explains how that works, and the tool limitations page lists what each tool is built to handle.
Start with the image compressor, check the new total against the 1.37 rule, and attach the result like any other file.
Our view: fix the file before you fix the delivery
We think most people reach for a delivery method when the real issue is the file. Someone with a 32 MB PDF opens a cloud account, uploads, sets permissions and writes a second email explaining the link. Often that PDF is five phone photos that could have been smaller before anyone made it.
Shrinking first has real advantages. The recipient gets an ordinary attachment. There is nothing to expire, no sign-in, no permission to get wrong. That matters when the recipient is a busy hiring manager, an admissions office or an accounts team.
It also matters where the processing happens. Documents and photos are often personal: ID pages, signed forms, pay stubs. Our tools run in your browser, so the file stays on your device while it is compressed or turned into a PDF. We designed the suite around that, and around the idea that a routine task should not need an account or an install.
When a file has to stay whole, a link with a password and an expiry date is the right tool. For everything else, a smaller file is the simplest message you can send.
IA
FAQ
What is the maximum file size you can send by email?
It depends on the provider. Personal Gmail and Outlook.com allow 25 MB, Outlook with an internet email account allows 20 MB, and Exchange business accounts default to 10 MB under Outlook's own limit. Because encoding adds about 37%, plan for files of roughly 18 MB or less.
How do I send a large file in Gmail?
Attach it normally. If the total goes over 25 MB, Gmail turns it into a Google Drive link. A smaller file is easier for the recipient, so compress or resize the images first. On a work or school account the limit is set by your administrator.
How can I send a PDF that is too large to email?
Find out what makes it heavy, which is usually images. Compress the images, rebuild the document with JPG to PDF, or merge trimmed parts with a PDF merger. If it must keep print quality, share it by a cloud link with a password and an expiry date.
Does zipping a file get it under the limit?
Sometimes, for text and uncompressed data, but rarely for PDFs, photos or video, because those are already compressed. Reducing image size or sharing a link works better.
Is a download link safe for confidential files?
It can be, if you set it up on purpose. Share with named people, use view-only access, add a password and an expiry date, and stop sharing once the recipient has the file.
Sources
- How to Send Large Files, Microsoft 365
- Reduce attachment size to send large files with Outlook, Microsoft Support
- Attachment size exceeds the allowable limit error, Microsoft Learn
- Send attachments with your Gmail message, Gmail Help
- Send Google Drive attachments in Gmail, Gmail Help
- Email Attachment Size Limits and Base64 Overhead, SMTP.dev
- Gmail Attachment Size Limit 2026, Email Analytics
- Huge Attachments up to 1 GB, Zoho Mail
- How to create a shareable link in Proton Drive, Proton
- How to Send Large Documents and PDFs, StrongFolder