How to Make a PDF Smaller for Email (Gmail, Outlook)
By Tooldesk team · · 3 min read
To make a PDF small enough to email, compress the images inside it. Open our Compress PDF tool, add the file, keep Recommended selected and select Compress PDF. Photos and scans are resized and saved more efficiently while text and lines stay exactly as they were, so the document still looks sharp and its text can still be selected and searched. Most image-heavy PDFs shrink by half or more. Your file is processed in your browser and never uploaded.
Email attachment limits
Gmail lets you attach up to 25 MB per email. Outlook and most work email systems have similar limits, often 20–25 MB, and some company servers set lower ones. The limit covers all attachments together, and email encoding makes files about a third bigger in transit, so a file just under the limit can still bounce.
A good rule: keep attachments under 10 MB if you can. They send faster, they don’t fill the recipient’s inbox, and they’re less likely to be blocked.
Steps to compress for email
- Open Compress PDF.
- Add your PDF.
- Choose a level:
- Light for documents that will be printed.
- Recommended for email. It is the best balance for most files.
- Strong for the smallest file while text stays sharp.
- Optional: tick Convert images to black and white for documents where colour doesn’t matter, such as scanned forms. It saves a lot more.
- Select Compress PDF and check the new size.
- Download and attach.
If the tool can’t make the file smaller, it tells you and keeps the original. That usually means the PDF is mostly text and fonts, which are already compact.
What makes a PDF big
| Cause | How to tell | Fix |
|---|---|---|
| Photos from a phone camera | Pages with pictures, file 5–50 MB | Compress with Recommended or Strong |
| Scanned pages | You can’t select text | Compress; add black and white for forms |
| Many pages | File size grows with page count | Split and send only what’s needed |
| Embedded fonts and vector drawings | Engineering drawings, maps | These compress little; share a link instead |
If it’s still too big
Send only the pages that matter. Use Split PDF to extract the pages the recipient needs. Several smaller attachments are fine too, but one tidy file is easier to handle.
Send it in parts. Split a large report into two or three files, email them separately, and let the recipient combine them with Merge PDF if needed.
Share a link. Gmail offers to put files over 25 MB in Google Drive and send a link. Outlook does the same with OneDrive. For very large files, a link is the better choice anyway.
Use Extreme for strict limits. If a system demands a very small file, the Extreme level redraws pages as images. It gets the smallest results, but text can no longer be selected. Our guide to compressing a PDF to 100 KB explains when that makes sense.
Built-in options
Mac: open the PDF in Preview, choose File → Export, and set Quartz Filter to Reduce File Size. It can over-compress images, so check the result.
Microsoft Word: if you made the document in Word, choose File → Save As, pick PDF, and select Minimum size (publishing online). Starting from the original document gives a smaller, cleaner PDF than compressing afterwards.
Phone scanner apps: most let you pick a lower quality or black-and-white mode before saving. Choosing it at scan time keeps files small from the start.
Questions people ask
Does compressing a PDF reduce quality?
Only for images. Text, fonts and lines are left untouched at Light, Recommended and Strong. Photos are resized to the size they are shown on the page, which is hard to notice on screen.
How do I compress a PDF on my phone?
Open our Compress PDF tool in your phone’s browser. It works on iPhone and Android without installing an app.
Why won’t my PDF get smaller?
It is probably mostly text, or its images are already compressed. Remove pages you don’t need, or send a link instead.
Is it safe to compress a confidential PDF?
With our tool, yes: the file is processed inside your browser and never sent to a server.