Compress PDF
Reduce PDF file size in your browser. Photos and scans are recompressed while text stays sharp, and your files never leave your device.
or drop them here
One or many PDFs. No size limit, nothing is uploaded.
How it works
PDF compression makes a file smaller by rewriting the parts that take the most space. Photos and scanned pages are scaled down to the resolution they are shown at and saved as JPEG, and the file structure is repacked without unused data. Text, fonts and vector graphics are kept as they are, so they stay sharp and searchable.
- Add your PDFs
Drop one file or a whole batch. A locked file asks for its password, which is checked on this device.
- Pick a level
Recommended suits most files. Light changes nothing you can see; Strong and Custom go further.
- Download
Every file shows its size before and after. A file that would shrink by less than 1% is kept as it was.
What each level does
| Level | Photos and scans | Best for |
|---|---|---|
| Light | Unchanged | Files that must stay exactly as they are |
| Recommended | 150 DPI, JPEG quality 75% | Email, sharing and reading on screen |
| Strong | 100 DPI, JPEG quality 55% | The smallest file for previews and upload size caps |
| Custom | 36 to 600 DPI, quality 5 to 100%, optional grayscale | Your own balance of size and detail |
What changes and what stays
Every level also removes objects nothing points to, stores identical image and font data only once, packs small objects into compressed object streams and recompresses uncompressed data. An image is scaled down only when it is at least 20% sharper than the target resolution and is only replaced when the new version is at least 5% smaller. Images are never scaled up, and a file that would shrink by less than 1% is left exactly as it was.
Why some PDFs barely shrink
Most of the size of a typical PDF sits in photos and scanned pages. A report that is mostly text, or one whose pictures are already small, has little left to remove, so expect a few percent at most. Embedded fonts are kept as they are, and a complete font for Chinese, Japanese or Korean text can take several megabytes on its own. Screenshots and diagrams keep lossless compression, because JPEG would blur their text; like photos, they are scaled down when they are sharper than the target resolution.
What is kept as it is
- Text, fonts and vector drawings: never converted to images unless you turn pages into images.
- Transparency: image masks are kept at full resolution.
- Links, bookmarks, form fields and tags: kept, except when pages become images.
- CMYK, palette, JPEG 2000 and 1-bit fax images: left as they are, because a browser cannot recompress them without shifting colors, losing detail or making them bigger.
Signed documents
Any change to a digitally signed PDF invalidates the signature. Compress the document first, then sign it.
Private by design
The PDF is opened, compressed and saved by code running in this page. Nothing is uploaded, there is no sign-up, no watermark and no limit other than your device's memory. Once your first file is open, the tool keeps working without a connection.
Frequently asked questions
Does compressing a PDF reduce its quality?
Light compression is lossless: it only repacks the file and removes unused data, so nothing on the page changes. Recommended and Strong recompress photos and scans, which can make them slightly softer, but text, fonts and vector graphics are not touched and stay sharp at any zoom. If a file would not get at least 1% smaller, the original is kept.
Are my files uploaded to a server?
No. The PDF is opened, compressed and saved by code running in your browser, so the file never leaves your device. There is no sign-up, no watermark and no file size limit other than your device's memory.
Why did my PDF barely get smaller?
Most of the size of a typical PDF is in photos and scanned pages. A PDF that is mostly text, or whose images are already small and compressed, has little left to remove. Embedded fonts are kept as they are, and a full Chinese, Japanese or Korean font can take several megabytes. Try Strong, a lower custom resolution, or turn pages into images for scanned documents.
What does turning pages into images do?
It saves every page as one JPEG picture at the resolution and quality of the level you pick. That gives the smallest file for scans and picture-heavy pages, but text can no longer be selected, searched or copied, and links, bookmarks and form fields are removed. Leave it off for documents people need to search or fill in.
Can I compress a password-protected PDF?
Yes. Enter the password when asked; it is checked on this device and never sent anywhere. The compressed copy is saved without the password, so protect it again if it needs protection. Digitally signed PDFs lose their signature when changed, so compress them before signing.