How to Make a PDF Smaller for Email (Under 25 MB or 20 MB)
By the UtilityNest team · · 5 min read
The landlord wants the signed lease back today. You scanned all 18 pages on your phone, attached the PDF, pressed send, and your email app came back with "attachment too large". The file is 38 MB. You are not sure what you did wrong.
Nothing, really. A PDF made from scans or phone photos is basically a stack of large pictures, and pictures are heavy. The fix is usually a two-minute job once you know which kind of PDF you are dealing with.
The short version: run the file through Compress PDF on the Recommended level. If it is still too big, try Strong and switch on grayscale for black-and-white paperwork. Pages you do not need can go with Delete PDF Pages, and anything truly huge can be split into parts.
The limits you are aiming for
| Email service | Attachment limit |
|---|---|
| Gmail | 25 MB (bigger files are offered as a Google Drive link) |
| Outlook.com / Hotmail | 20 MB (bigger files can go via OneDrive) |
| Yahoo Mail | 25 MB |
| iCloud Mail | 20 MB (Mail Drop sends up to 5 GB as a link) |
| Work email | Set by your organization, often lower |
Two catches. Attachments are encoded for sending, which makes them roughly a third bigger inside the message, so a 19 MB file can fail a 25 MB limit. And the recipient's mail server has its own limit. Aim for under 10 MB and you avoid nearly all bounces.
First, why is your PDF so big?
Open it and try to select a sentence with your cursor.
- The text highlights normally: it is a text-based PDF, exported from Word or similar. These are usually small, unless they contain big photos.
- Nothing highlights, the page acts like one picture: it is a scanned PDF. Each page is a photo, often stored at very high resolution. This is the usual reason a PDF is tens of megabytes.
A worked example: the 38 MB lease
18 phone-scanned pages, 38 MB, needs to go by Gmail. In Compress PDF:
- Drop the file in and choose Recommended (images re-saved as JPEG at 72%, capped at 2000 pixels).
- Click Compress. The before and after sizes appear side by side.
- For a scan like this, a cut of well over half is normal; the tool's own guidance is that scans often shrink by 50 to 90%. Say it lands around 6 MB: done.
- Still over? Run it again on Strong (JPEG 50%, up to 1300 px) and tick grayscale, which suits black-and-white paperwork.
38 MB, bounced by Gmail and Outlook, takes ages to open on a phone.
A few MB, sends instantly, text still perfectly readable on screen and in print.
Which compression level to pick
| Level | What it does | Good for |
|---|---|---|
| Lossless | Cleans up the file structure, images untouched | Text-based PDFs, or when quality must not change |
| Light | JPEG 85%, images up to 3000 px | Photo-heavy documents you may print |
| Recommended | JPEG 72%, up to 2000 px | Email and sharing, most of the time |
| Strong | JPEG 50%, up to 1300 px | Smallest files, reading on screen |
Only embedded images are recompressed. Text and vector drawings are never turned into pictures, so a contract stays sharp and searchable. If compressing cannot make a file smaller, the tool says so and keeps your original instead of handing you a bigger file. Everything runs in your browser, so confidential documents are not uploaded, and you can do up to 20 files at once.
A mostly-text PDF that is still large often has one or two huge photos inside, like a full-resolution logo or a cover image. Recommended handles those without touching the text, so it is still the right first try.
Drop pages nobody needs
Blank backs of scanned pages, duplicate cover sheets and long appendices all add weight. Delete PDF Pages lets you click pages to remove them, or type ranges like 2, 5-7; the Even button marks every even page in one go, which is perfect for a double-sided scan full of blank backs. If the recipient only asked for a few pages, Extract PDF Pages saves just those.
Split it and send it in parts
When a document must stay at full quality, split it. In Split PDF, choose By ranges and type 1-20, 21-, or use Every N pages for equal chunks. Send the parts in separate emails labeled "part 1 of 2" and "part 2 of 2".
Other ways to shrink a PDF
Re-export from the original program
If you made the PDF yourself in Microsoft Word on Windows, choose File > Save As, pick PDF and select Minimum size (publishing online). Pictures are downsampled, which often cuts the size dramatically.
macOS Preview
Choose File > Export and set Quartz Filter to Reduce File Size. Quick and free, but it can be harsh on images, so check the result before sending.
Send a link instead
Gmail offers a Drive link for anything over 25 MB, Outlook.com does the same with OneDrive, and Apple Mail has Mail Drop. Double-check the sharing permission so the recipient can actually open it.
Quick answers
Will compressing make my PDF blurry?
Lossless changes nothing visible. Recommended is hard to tell apart on screen. Strong can soften photos but keeps typed text crisp, because text is never converted to images.
Why did my PDF only shrink a few percent?
It is probably text-based and already efficient. There is little to squeeze; delete pages or split it if you are still over the limit.
Does zipping a PDF make it smaller?
Barely. PDFs are already compressed inside, so a ZIP saves very little.