How to Compress a PDF for Email (Without Ruining It)
You attach a PDF, press send, and the email bounces back: attachment too large. Gmail caps attachments at 25 MB, Outlook.com at 20 MB, and many job portals, government sites and school systems allow only 1–5 MB. The good news is that most oversized PDFs can be shrunk dramatically — often by 70–90% — without anyone noticing a difference.
Why some PDFs are so big
Text is cheap. A 50-page report with nothing but text and a few fonts is usually well under 1 MB. What makes a PDF heavy is almost always pictures:
- Scans. Every scanned page is a full-page photo. A scanner set to 600 DPI in colour produces enormous images, even for a plain white page with black text.
- Phone photos. A modern phone photo is 12–48 megapixels. Drop ten of them into a document and you have a 40 MB PDF.
- Exported presentations. Slides with full-resolution background images add up fast.
Screens only need a fraction of that detail. A typical laptop shows roughly 100–150 pixels per inch, so an image stored at 600 DPI carries sixteen to thirty-six times more pixels than anyone will ever see.
Pick the right compression level
In the Compress PDF tool you can choose between four levels. They all work by resampling the images inside the PDF to a lower resolution and re-saving them as efficient JPEGs:
| Level | Image resolution | Best for |
|---|---|---|
| Light | 200 DPI | Documents you might print |
| Recommended | 144 DPI | Email, sharing and reading on screen |
| Strong | 100 DPI | Upload forms with tight limits |
| Maximum | Pages become images | Scanned documents that must be tiny |
With the first three levels, text stays sharp and selectable — only the pictures change. Maximum is different: each page is turned into one compressed image. That gives the smallest files for scans, but you can no longer select or search the text, so use it only when nothing else gets you under the limit.
Need an exact size? Use a target
If a website tells you “maximum 2 MB”, you do not want to guess. Switch the mode to Fit a file size and type the limit. The tool starts with the gentlest setting and only goes stronger until the file fits — so you get the best quality that is still under the limit. There are ready-made pages for common limits, such as compress PDF to 1 MB and compress PDF to 200 KB.
Tips for even smaller files
- Black & white helps scans. A scanned contract does not need colour. Turning on Convert images to black & white often cuts the size by another third.
- Remove pages you do not need. Cover pages, blank pages and appendices all count. Delete pages first, then compress.
- Split instead of squeezing. If a 60 MB report has to go by email, splitting it into two or three parts can keep the quality you need.
- Text-only PDFs won’t shrink much. If the result is barely smaller, the PDF is already efficient. In that case you get your original file back, unchanged, instead of a worse copy.
Is it safe to compress a confidential PDF online?
Most online compressors upload your file to a server, process it there and let you download the result. That means a copy of your contract, bank statement or medical letter sits — at least for a while — on someone else’s computer.
FileCrafty works differently: the compression code runs inside your browser, on your own device. Your PDF is never uploaded, which you can verify by switching off your internet connection after the page loads — the tool keeps working.
Quick answer
Open Compress PDF, drop your file in, keep Recommended and download. For a hard upload limit, choose Fit a file size and enter the number. That’s it.