How to make a PDF smaller

Most oversized PDFs are big for one reason: the images inside them. That is where the saving is.

An email limit of 10 MB and a 40 MB attachment is a common predicament. What can be done about it depends entirely on why the file is large.

Step-by-step

1. Add your PDF.
2. Choose a compression level.
3. Compare the result before you commit — check the pages that matter most.
4. Download.

Where the size actually is

A text-only PDF of a hundred pages is often under a megabyte. A three-page scan can be forty. Text is compact; images are not, and scanners produce images at high resolution by default.

So compression works by reducing image resolution and quality. If your PDF is genuinely text, there is very little to remove and the tool will not pretend otherwise — a file that is already small will not shrink much, and any tool claiming otherwise is discarding something.

How far to go

• For email or screen reading, a substantial reduction is usually invisible.
• For printing, compress lightly. Artefacts invisible on screen show clearly on paper.
• For archival or legal copies, do not compress. Send it another way instead.

Alternatives worth trying first

If only some pages are needed, extract those pages — sending three pages instead of ninety beats compressing all ninety. And if the file is a scan, check whether it was scanned at 600 DPI when 200 would have done; rescanning is often better than compressing.

Frequently asked questions

Why did my PDF barely shrink?

Because it is mostly text, which is already compact. Compression works on images, so a text document has little to give up.

Does compressing lose quality?

For image content, yes — that is the mechanism. Text and vector graphics are unaffected. Compress lightly if the document will be printed.

What is the best way to email a large PDF?

Send only the pages needed, if that is an option. Otherwise compress for screen reading, or use a file-sharing link for anything that must stay at full quality.