How PDF Compression Works — and When to Use Max Compression Mode

PDF files can grow surprisingly large, especially when they contain high-resolution images, embedded fonts, and metadata. Knowing how PDF compression works helps you choose the right approach and reduce PDF size effectively.

What Makes PDFs Large?

A PDF is essentially a container that bundles together text, vector graphics, images, fonts, and metadata. The images embedded within a PDF are often the biggest contributors to file size — a scanned document or a presentation with large photos can easily balloon to tens of megabytes.

Normal PDF Compression

In standard compression mode, CompressAndGo uses two main techniques to reduce PDF size for free:

1. Image Recompression — The tool identifies JPEG images embedded in the PDF and recompresses them at a lower quality setting. This alone can dramatically reduce file size.
2. Metadata Stripping — Author names, creation dates, software tags, and other metadata are removed. While small individually, they add up.
3. Object Stream Optimization — PDF internal objects are reorganized into compressed streams, reducing the overall byte count.

This approach preserves all text as selectable vector content, meaning your PDF remains fully searchable and copy-pasteable after compression.

Max Compression Mode (Rasterization)

For extremely large PDFs — or when you need to hit a very small target size — CompressAndGo offers a Max Compression mode. This works differently:

Each page of the PDF is rendered to a canvas (like taking a screenshot of it), and those images are reassembled into a new PDF. This is called rasterization. The result is a much smaller file, but with an important trade-off: text in the output is no longer selectable or searchable because it has become part of the image.

Use Max Compression when: You need the absolute smallest file size, the PDF is image-heavy already, or searchable text is not required.

Stick to Normal mode when: You need selectable text, the PDF contains forms, or you need to copy content from the document.

How to Reduce PDF Size for Free

With CompressAndGo, reducing PDF size is straightforward: drag your PDF into the tool, set your target size (e.g., 200 KB), and the AI-powered engine automatically applies the best strategy. No upload, no account, no cost — just fast, private PDF compression in your browser.