Compress PDF
Reduce PDF file size at the level you choose
Files up to 200 MB are compressed with our full engine (images, fonts, and structure). Larger files, up to 700 MB, get a lighter in-browser optimization (structure only).
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About Compress PDF
PDF Compress makes a PDF smaller on our pdf-tools server, at the level you choose. Recommended and Extreme re-encode the larger pictures as JPG, resampled from the size they are displayed at on the page (150 dpi and 72 dpi); a picture that needs no resizing is replaced only when its JPG is clearly smaller, CMYK and indexed-color pictures, image masks, and pictures with a color-key mask are left as they are, and a picture with a transparency mask keeps its transparency. Lossless leaves every picture alone. At every level, Type 1 fonts are converted to the compact CFF format with Adobe's tx, duplicate TrueType subsets are merged, and the file structure is repacked. Page text and vector drawings are never rewritten. Files up to 200 MB get this full engine.
How to compress a PDF
- 1Choose your PDF; its original size appears under the name.
- 2Pick "Extreme", "Recommended", or "Lossless".
- 3Click "Compress PDF" and follow the upload and compression bar; "Cancel" stops it.
- 4Compare the sizes before and after, then click "Download" to get the -compressed.pdf file.
Formats and limits
- Input
- Levels
- Extreme (pictures at 72 dpi), Recommended (150 dpi), Lossless (pictures untouched)
- Full engine
- Files up to 200 MB, on our pdf-tools server
- Larger files
- Files over 200 MB: refused on phones and tablets; on a computer, only a lighter structure-only optimization runs, in your browser, within the limit shown on the page
- Usage limits
- Each network may compress a limited number of PDFs per hour and per day, whatever their size; files over 4 MB are uploaded in chunks
- No gain
- If no smaller file can be made, nothing is offered for download
Where your file is processed
Files up to 200 MB are compressed by our own pdf-tools service on Railway. Up to 4 MB, the file passes through our site and the service's temporary folder is deleted when the request ends. A larger file is uploaded in chunks to our server: the upload is deleted once the compressed file is ready, and that file as soon as this page has received it in full, or after 15 minutes at the latest. Files over 200 MB are handled differently: on a computer, only a lighter optimization runs, in your browser.
Frequently asked questions
How much smaller will my PDF get?
0.1% to 78.8% smaller in our test of September 23, 2026, depending on the content and the level: a 15-page research paper lost 35.4% with Lossless, 40.6% with Recommended and 43.0% with Extreme; a PDF of six photos lost only 0.1% with Lossless, 15.2% with Recommended and 78.8% with Extreme. When a level cannot make the file smaller, you get a message and no file.
Does Lossless change how my pages look?
No. Lossless re-encodes no picture: it converts Type 1 fonts only after checking that every glyph is still there with the same outline bounds, merges duplicate font subsets, and repacks the structure. In the same test, every page of the research paper rendered pixel-identical to the original in two independent renderers.
Can I compress a password-protected PDF?
Yes, if it opens without a password. A PDF that asks for a password to open is refused with a message pointing to Unlock PDF; a PDF that opens freely but restricts printing or copying is compressed like any other file.
Is there a limit on how often I can compress?
Yes. To keep the service free for everyone, each network may compress a limited number of PDFs per hour and per day, whatever their size; past that, the page tells you to try again later. A file over 4 MB is also uploaded in chunks through our server.
Tips and tricks
- ✓For a PDF made of photos, try Extreme: in our test it saved far more on pictures than Recommended.
- ✓Over 200 MB, split the file with PDF Split and compress each part with the full engine.