Compress PDF
Make a PDF smaller — losslessly, or much smaller by rasterising.
Everything runs inside your browser. Your files never leave your device.
Drop your file here
.pdf · they stay on this device
Ask about Compress PDF
Questions about what this tool does, which option to pick, or what it can and cannot handle.
The question you type here is sent to an AI provider to be answered — your files and whatever you put in the tool above are not, and the assistant cannot see them. Answers are generated and can be wrong. The tool itself is not guessing: it runs deterministic code on your device.
About the Compress PDF
PDFs are large for a small number of predictable reasons, and knowing which one applies to your document determines whether compression will help at all.
Scanned documents are large because every page is a photograph. A 300-dpi colour scan of an A4 page is several megabytes before anything else, and a forty-page scan is a very large file made of forty large images. That is the case compression helps most, and re-encoding those images at a sensible quality routinely removes most of the size with no meaningful loss for reading on screen.
Text-based PDFs exported from a word processor are usually small already, and where they are not the cause is embedded fonts or an unnecessarily large image on the cover. Compression will do very little to a document that is mostly text, because text in a PDF is already stored efficiently.
This re-encodes embedded images at a quality you choose and rewrites the document structure. The before and after sizes are reported, so a document that does not shrink tells you immediately that images were not the problem.
The quality choice is a genuine trade rather than a free win. Downsampling images to 150 dpi is invisible on a screen and visible in print; 300 dpi is the usual floor for anything that will be printed. If the document is going to a printer, compress less than feels efficient.
Everything happens in this tab, which matters because the documents people most want to shrink — a signed contract for email, a scanned identity document for a form — are precisely the ones that should not be uploaded to achieve it.
How to use it
- 1Drop in the PDF.
- 2Choose a quality level. Lower is smaller; check the result if the document will be printed.
- 3Compare the before and after sizes.
- 4If it barely shrank, the document is mostly text and compression has little to work with.
Questions
- Why did my PDF barely get smaller?
- Because it is mostly text, which is already stored efficiently. Compression works on embedded images, so a scanned document shrinks dramatically and a word-processor export usually does not.
- Will compression make my document unreadable?
- Not at moderate settings — text is not re-encoded, only images are. Aggressive settings soften scanned pages and show on print. Compress less if the document is going to a printer.
- Is the compression reversible?
- No. Image re-encoding discards data permanently. Keep the original file, and compress a copy.
- Are my documents uploaded?
- No. The document is read and rewritten in this browser tab, which matters given that the files people most want to shrink are contracts and scanned identity documents.