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5 Ways to Reduce PDF File Size Online

February 11, 20256 min read

Why Are PDFs So Large?

PDFs often contain embedded fonts, high-resolution images, metadata, and unused objects. A 10-page document with photos can easily exceed 50 MB. Here are 5 proven ways to shrink them.

1. Compress the Images Inside

Images are the biggest contributor to PDF size. Many PDFs contain 300 DPI images when 150 DPI is sufficient for screen viewing. Compress your images with our Image Compressor before inserting them into documents.

2. Remove Unnecessary Pages

If you only need specific pages from a large PDF, extract just those pages. Our PDF Merger can also help you combine only the pages you need into a single, smaller document.

3. Use "Save As" Instead of "Save"

When you edit a PDF repeatedly, deleted content remains in the file as hidden data. Using "Save As" creates a clean copy without this bloat. This alone can reduce file size by 10-30%.

4. Flatten Form Fields and Annotations

Interactive form fields, comments, and annotations add significant overhead. If you don't need them to be editable, flatten them into the document.

5. Choose the Right Export Settings

When creating PDFs from Word, PowerPoint, or design tools, look for "web optimized" or "reduced size" export options. These automatically downsample images and remove unnecessary data.

Quick Size Comparison

  • Unoptimized: 52 MB (300 DPI images, embedded fonts)
  • Image-compressed: 18 MB (150 DPI, JPEG quality 80)
  • Fully optimized: 8 MB (web-optimized export, flattened)