How to reduce PDF file size for email and upload portals
"The file is too large." Almost everyone who has tried to upload a scanned document to a government portal, a university or job application site, or to send it by email has seen this message. The limits are strict: Gmail accepts attachments up to 25 MB, and many portals allow only 2 to 5 MB per document. This guide explains why PDF files grow so big and how to shrink them in a minute without making them hard to read.
Why is my PDF so large?
Text takes very little space – a hundred pages of plain text often weigh less than one megabyte. The size comes from images:
- Scanned documents. Every scanned page is really a photo. At 300 dpi in color, a single A4 page can easily be 1–3 MB.
- Phone photos. A PDF made from gallery pictures inherits their size – 4 to 6 MB per photo.
- Presentations and catalogs with many full-resolution images.
You don't need that much resolution for reading on screen or ordinary printing. Lowering image resolution to 150 dpi makes the file several times smaller, and the difference is barely visible.
The fastest way: online compression
- Open Compress PDF.
- Select one or more PDF files (or drop them into the box).
- Keep the "Recommended" level and click "Compress PDF".
- Download the smaller file. The tool shows how much was saved, for example from 12 MB down to 1.8 MB.
If the file is still too large for the portal, repeat with "Strong compression". Text stays readable while images lose some sharpness – perfectly acceptable for documents, certificates and forms.
Tip: if you are sending several documents, select them all at once. They are compressed with the same level and downloaded together in one ZIP archive.
Which compression level should I pick?
| Situation | Level |
|---|---|
| Email, archiving, most portals | Recommended (150 dpi) |
| Portal with a 1–2 MB limit per file | Strong (72 dpi) |
| A document that will be printed | Light (300 dpi) |
What if that is still not enough?
- Remove unnecessary pages. Blank pages, covers and duplicates only add weight. Delete them with Remove pages.
- Split the document. If the portal accepts several files, divide a large PDF with Split PDF.
- Scan smarter. Next time choose 150–200 dpi and black-and-white or grayscale for text documents. The file can be up to ten times smaller.
- For phone photos, use the "Smaller file" option in JPG to PDF.
Is it safe?
Image compression needs server-side processing, so the file is sent over an encrypted connection. It exists on our server only while it is being processed – a few seconds – and is deleted as soon as the result is returned. We make no copies and never read your documents.
In short
A large PDF is almost always caused by images at an unnecessarily high resolution. Recommended compression shrinks most scanned documents by 50–90%, which is enough for email and most portals. For the strictest limits, use strong compression and remove the pages you don't need.