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Compress PDF

Reduce PDF file size, with the real before-and-after figures and a clear statement of what each mode changes.

What Compress PDF does

Most oversized PDFs are large because of the images inside them. A document that is mostly text has very little slack, which is why it is entirely normal for compression to achieve almost nothing on a text-only file.

Three modes are offered. The structural mode rewrites the document's internal objects more efficiently and changes nothing you can see. The two stronger modes redraw each page as a JPEG image at a reduced resolution, which shrinks scanned documents dramatically and removes the text layer.

  • Structure-only compression that keeps text selectable
  • Two rasterising modes that trade text for a much smaller file
  • True output size reported, including when nothing was saved
  • The original file offered instead when the result would be larger

How to use Compress PDF

  1. 1

    Add your PDF

    Drop in the file you want to shrink.

  2. 2

    Choose a mode

    Start with the structural mode if the text layer matters. Choose a rasterising mode for scans, or when the file must fit a hard size limit.

  3. 3

    Compare the result

    The reported size is the real size of the output. If it is not smaller, the tool says so.

  4. 4

    Check before you rely on it

    After a rasterising pass, open the result and confirm the pages are still readable at the size you need.

Limits and known behaviour

  • A clean text-based PDF may not shrink at all. There is nothing wrong when that happens; the file simply has no redundancy to remove.
  • The rasterising modes convert pages to images. Text stops being selectable and searchable, links and form fields are lost, and screen readers can no longer read the document.
  • Compression is lossy in the rasterising modes. Quality that is removed cannot be recovered by running the file through again.
  • Re-compressing an already compressed PDF usually adds artefacts for little further saving.
  • Password-protected PDFs cannot be opened. The PDF library used here has no decryption support, so an encrypted file is rejected rather than partially processed. Remove the password in a PDF reader first.
  • There is no file size limit, but the whole document is held in memory while it is processed. Very large or image-heavy files can make the tab slow or unresponsive on a device with limited RAM.

Privacy and data handling

Runs entirely in your browser

  • Your PDF is read into this page by the browser and rebuilt here. It is never uploaded, so no copy of it exists on any server.
  • The original file on your disk is not modified; the tool produces a new file for you to download.
  • Nothing is kept after you close the tab.

Site-wide data handling, including analytics and advertising, is described in the privacy policy.

Frequently asked questions

Why did my file get bigger?

Rewriting a document's structure occasionally produces a larger file, typically when the original was already efficiently packed. When that happens the tool reports it and offers the original file rather than the larger one.

Which mode should I use for a scanned document?

A rasterising mode. Scans are already images, so there is no text layer to lose, and reducing the image resolution is where the saving comes from.

Will compression make my document unreadable?

It can if you choose the strongest mode on a document with fine print. Always open the output and check before discarding the original.