Oxford PDF

Compress PDF

Reduce stored PDF data without lowering image quality.

Free to useNo account requiredFiles stay in your browser

A PDF to optimise

Choose an unlocked PDF to optimise its stored data.

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How to compress a PDF

  1. Open a PDF

    Choose an unlocked PDF.

  2. Optimise stored data

    Select Compress PDF to optimise its stored data.

  3. Compare and download

    Compare the original and new sizes, then download a copy.

Before you save

  • Lossless compression does not resize images or flatten pages; it cannot guarantee a smaller file.
  • Signed, encrypted and repaired PDFs are refused. Check the result before replacing a working copy.

Questions about lossless compression

Does compression reduce image quality?

This tool uses lossless compression. It optimises stored data without lowering image resolution.

Why did my PDF stay the same size?

Many PDFs are already compressed. The tool keeps a copy when further lossless reduction is not useful.