How to Compress a PDF Without Losing Quality

PDF files can grow large quickly — especially those containing high-resolution images, embedded fonts, or complex graphics. Compressing a PDF reduces file size, making it easier to share, upload, and store.

Why PDFs Get Large

The main culprits are:

• High-resolution images — Photos embedded at 300 DPI or higher are the biggest size contributors.
• Embedded fonts — Every font in a PDF is stored as binary data.
• Redundant streams — PDFs can accumulate unused data from edits.

Compression Levels Explained

Most PDF compressors offer three levels:

• Low compression — Minimal quality loss. Best for documents that will be printed.
• Medium compression — Balanced. Images are slightly downsampled. Good for most use cases.
• High compression — Maximum size reduction. Best for web use or email attachments.

How to Compress a PDF Online

1. Go to our [Compress PDF](/tools/compress) tool.
2. Upload your PDF file.
3. Select your desired compression level.
4. Download the compressed file — you'll see the size reduction instantly.

Tips for Better Compression

• Flatten form fields before compressing — form data adds overhead.
• Remove hidden layers if the PDF was created in design software.
• Re-save from the source when possible — export a new PDF from Word/InDesign at lower quality rather than recompressing.