How to Compress a PDF Without Losing Quality

A 40 MB PDF that won't attach to an email is one of the most common document headaches. The good news: most PDFs can be made dramatically smaller, and you can control the trade-off between size and quality.

Two ways to make a PDF smaller

There are two very different approaches, and picking the right one matters:

• Lossless optimisation re-packs the file's internal structure without touching the content. Text stays crisp and selectable. Savings are modest but there's zero quality loss.
• Image compression re-encodes the pages as compressed images. This can cut file size enormously, which is perfect for scans and image-heavy PDFs — but text becomes part of the picture.

Which should I use?

• Text documents (reports, contracts, ebooks): start with Optimize PDF. It keeps everything selectable.
• Scans and photo-heavy PDFs: use Compress PDF and choose a level from Low to Maximum. You'll see the estimated size reduction before you download.

Step by step

1. Open Compress PDF.
2. Pick a compression level — Medium is a great default.
3. Compare the new size to the original, then download.

Find out what's making your PDF big

Not sure why a file is so large? Run it through the PDF Size Analyzer first. It shows each page's byte contribution as a bar chart, so you can see whether one scanned page is the culprit.

Tip: if you only need a few pages, splitting or deleting pages can shrink a file far more than compression alone.