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How-To Guide

How to Compress a PDF File

PDF files can grow huge when they contain high-resolution images or embedded fonts — making them slow to email or upload. Compressing a PDF reduces file size by re-encoding embedded images at lower resolution, removing unused fonts, and stripping metadata. The right compression preserves text and document structure while shrinking images intelligently.

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Step-by-step instructions

  1. 1

    Upload your PDF file

    Select your .pdf file. The compressor analyses embedded images, fonts, and metadata to find the largest reducible elements.

    Go to converter
  2. 2

    Choose compression level

    Light (90% original size, minimal quality loss) — best for documents already optimized. Medium (50% original size) — best for emailing typical reports. Strong (20% original size) — best for screen viewing where image fidelity matters less.

  3. 3

    Download the compressed PDF

    Compare the file size before and after. Open the PDF and check that text remains crisp and images are acceptable for your use case.

Why convert PDF to PDF?

Bloated PDFs slow workflows. Compression brings them back to reasonable sizes for email, the web, and cloud storage — usually with no visible quality loss.

Your files never leave your device

FormatDrop runs the conversion engine entirely inside your browser using WebAssembly. No file upload. No server. Nothing stored. You can verify this by opening DevTools → Network tab and watching: zero upload requests.

Frequently asked questions

Will compressing a PDF lose quality?
It depends on the level. Light compression strips metadata and recompresses images at slightly lower quality — visually imperceptible. Medium recompresses images at 150 DPI — fine for screen but visible if printed. Strong recompresses at 72 DPI — clearly degraded if printed.
FFmpeg or Ghostscript for PDF compression?
Ghostscript: `gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf`. PDFSETTINGS options: /screen (smallest), /ebook (medium), /printer (high quality), /prepress (best quality).
Why is my compressed PDF still large?
PDF compression mainly reduces image data. If your PDF contains mostly vector content (text, shapes), there's little to compress. Embedded fonts, attachments, and JavaScript also add size — strip them with `qpdf --linearize --object-streams=generate`.
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