How to compress a PDF
- Upload the PDF you want to make smaller.
- Pick Lossless optimise for text documents, or Strong (image-based) for scans and photo-heavy files.
- In strong mode, choose a resolution and JPEG quality. 110 DPI at 70% is a good balance for on-screen reading.
- Click Compress PDF and compare the original size, the new size and the percentage saved, then download.
Two ways to reduce PDF size
Lossless optimisation rebuilds the file structure and stores internal objects more compactly. Text, fonts, links and image quality stay exactly the same. The saving depends on how the original was made: files exported by some apps shrink noticeably, while already-optimised files may not get smaller at all.
Strong compression renders each page as an image at the resolution you choose and saves it as a compressed JPEG, then rebuilds the PDF. This can shrink scanned documents dramatically, but text is no longer selectable or searchable and links stop working. We show a clear warning before you use it.
This tool never pretends. If the result isn’t smaller than your original, it says so and doesn’t offer the larger file as a “compressed” download. Rendering uses PDF.js and rebuilding uses pdf-lib, both running in your browser.
When PDF compression helps
- Getting a scanned contract under an email attachment limit.
- Uploading documents to government or university portals with a 2 MB or 5 MB cap.
- Sharing a photo-heavy brochure on a slow connection.
- Archiving large scans to save storage space.
Compress PDF FAQ
Why did my PDF not get smaller?
Some PDFs are already efficient, so lossless optimisation has nothing left to remove. Try strong mode for scans, or keep your original.
Will compression make text blurry?
Lossless mode never changes how anything looks. Strong mode turns pages into images, so choose a higher DPI if you need sharp small text.
Can I compress a password-protected PDF?
No. Remove the password first, compress the file, then protect it again with our Protect PDF tool if needed.