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Compress PDF Online — Reduce PDF File Size

Compress a PDF online for free. Images are re-encoded and scaled down; text stays sharp and selectable, and nothing is uploaded.

Runs in your browser — nothing is uploaded. Verify it

About the Compress PDF Online — Reduce PDF File Size

Compress PDF files in your browser — images are re-encoded at 80–95% quality and reduced to the resolution they are actually shown at, so the text stays sharp and the file still gets much smaller.

Large PDFs are slow to upload, download, and email.

How to use the Compress PDF Online — Reduce PDF File Size

  1. Add your PDF, or drop it in.
  2. That is the whole instruction — it compresses itself. The tool tries several settings in turn and keeps the smallest result, never cutting more than 95% of the file away, so the quality stays as high as that ceiling allows.
  3. Download the compressed PDF. The row tells you the quality and resolution that were applied.

Frequently asked questions

How do I compress a PDF?

Open your PDF in the tool — that is the whole instruction. Compression starts on its own and the row is ready in a moment with a Download button; there is nothing to choose and nothing to click. The row shows how much was saved and exactly which quality and resolution were applied. Compression runs entirely in your browser with pdf-lib — nothing is uploaded.

Will compression reduce my PDF quality?

The text does not change at all — words stay sharp, selectable and searchable, because only the images inside the document are touched. Images are re-encoded at a JPEG quality between 80% and 95%, and reduced to the resolution they are actually displayed at. An image that would not come out smaller is left exactly as it was, so the tool can never make a file bigger or make an image worse for nothing.

What resolution are the images reduced to?

The tool decides, file by file. Images are reduced to the resolution they are actually shown at — measured against the size they occupy on the page — by trying a series of targets from 300 dpi down to 96 dpi and keeping the smallest result that does not cut more than 95% of the file away. A 300 dpi scan of a full A4 page typically ends up around 96 dpi: a third of the width, about a ninth of the pixels, and still sharp on screen and in print. A small logo drawn at 120pt is reduced much further, because it never needed 2400 pixels in the first place. This is where nearly all of the saving comes from, which is what lets the quality stay high.

How much smaller will my file get?

It depends on how much spare resolution the file carries. A 300 dpi scan of an A4 page typically drops by around 90%. The tool always stops at a 95% reduction, so a file can never be cut down to nothing in the name of saving space. A document already stored at screen resolution and a low JPEG quality has nothing to give, and the tool says so rather than pretending it helped.

Are my files uploaded to a server?

No. All compression happens in your browser. Your file never leaves your device.

Does compression keep my bookmarks and links?

Yes. The document is edited in place rather than rebuilt, so bookmarks, page labels, links and embedded files all survive — only the images are re-encoded.

Is the document metadata removed?

Yes, automatically. The document's descriptive metadata is cleared: title, author, subject, keywords, creator, producer, the creation and modification dates, and the XMP packet. Bookmarks, page labels, links and embedded files are all kept. It is a few kilobytes of text that no longer serves any purpose, and on a PDF with no images left to re-encode it can be the only saving there is.

Can I compress a password-protected PDF?

No. Compressing means decoding and re-encoding the images, and those are exactly the parts a password protects — a "compressed" copy would come out as garbage. Remove the password first, or print the file to a new PDF, then compress that. The tool tells you when it refuses a file, and why.

Is there a page limit?

No hard limit. The tool scans the pages for images first and then compresses them a few at a time, so long documents stay responsive instead of freezing the tab.

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