How to compress a PDF
- Select one or more PDFs, or drop them onto the page.
- Choose a compression level: Light keeps the most quality, Recommended balances size and quality, and Strong makes the smallest files.
- For scanned documents that must be as small as possible, consider the option that turns pages into images.
- Click Compress PDF, check the size saving, and download.
Where PDF size comes from
In most large PDFs the bulk of the file is images: scanned pages, photos and screenshots stored at far higher resolution than a screen or office printer needs. Compression lowers the resolution of oversized images and re-encodes them more efficiently, then cleans up the file structure. Text, vector graphics and links are left as they are, so text remains sharp and searchable.
Choosing a compression level
- Light – minimal visible change. Good for documents you will print or for detailed photos.
- Recommended – a strong reduction that still looks clean on screen and on office printers. The right choice for most email attachments.
- Strong – smallest files for strict upload limits; fine photo detail and small print in images may soften.
The page-to-image option re-renders every page as a picture. It can shrink heavy scans dramatically, but text in the result is no longer selectable or searchable, so use it only when size matters more than text.
Why some PDFs barely shrink
A PDF made mostly of text, or one that has already been optimised, may only get slightly smaller because there is little image data to reduce. In that case, try removing unneeded pages with Delete PDF Pages, or run Optimize PDF for structural clean-up. Compression happens in your browser, which also means confidential documents are never uploaded to a compression server.
Frequently asked questions
How much smaller will my PDF get?
It depends on the content. Image-heavy and scanned PDFs often shrink by more than half; text-only PDFs may barely change. The result screen shows the exact saving.
Will the text become blurry?
No, unless you choose to convert pages to images. Normal compression only re-encodes images; text stays as sharp vector text.
Can I compress several PDFs at once?
Yes. Add multiple files and download the results individually or together as a ZIP.
Is my PDF uploaded to a server for compression?
No. The PDF is compressed in your browser and never leaves your device.
What if the compressed file is bigger than the original?
That can happen with files that are already well optimised. In that case, keep your original file; it is already as compact as it is likely to get.