Compress PDF
Reduce PDF file size by re-rendering pages as compressed images. Adjustable quality for the perfect balance between size and clarity.
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Drop a PDF file here or click to browse
How PDF Compression Works
This tool uses two compression strategies and picks the smallest result:
- Lossless re-save — Strips unused objects and metadata, keeping text selectable. Works best for text-heavy PDFs.
- Image-based compression — Renders each page as a JPEG at your chosen DPI and quality. Works best for scanned documents and image-heavy PDFs.
Quality Guidelines
- 80-95% — Minimal quality loss. Best for documents with fine text or detailed graphics
- 60-80% — Good balance. Suitable for most documents, reports, and presentations
- 30-60% — Aggressive compression. Good for scanned documents and image-heavy files
Tips for Best Results
- PDFs with embedded high-resolution images see the most size reduction
- Text-only PDFs may not compress much (they're already small)
- Use 150 DPI for a good balance between quality and file size
- Use 72 DPI for maximum compression when screen viewing is the only use case
Limitations
- If image-based compression is used, the output will not have selectable text. The tool shows which method was used after compression.
- Text-heavy PDFs that are already well-optimized may show little or no size reduction — this is expected.
- All processing happens in your browser — very large PDFs (50+ pages) may take longer depending on your device.
Frequently Asked Questions
The tool runs entirely in your browser using pdf-lib.js. It re-encodes embedded images at a lower quality setting, which is where most file size savings come from. Text, fonts, and vector graphics remain untouched, so document readability is preserved.
Yes. Everything happens 100% client-side in your browser. Your PDF is never uploaded to any server. You can confirm this by opening your browser's Network tab — no file data is transmitted. Your documents remain completely private.
There is no hard limit since processing uses your browser's memory. Most modern devices handle files up to 100—200 MB without issues. Very large files may take longer or require a device with more available RAM.
It depends on the content. Image-heavy PDFs such as scanned documents, photo albums, and brochures can often shrink by 50—80%. Text-heavy documents with few images typically see 10—20% reduction since text data is already compact.
Text and vector elements stay identical. Embedded images are re-encoded at a reduced quality, which may introduce minor visual differences at high zoom. For most use cases like emailing or web sharing, the difference is imperceptible.