How to Compress a PDF
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Reduce PDF file size by up to 80% without losing readability — directly in your browser, with no file uploads and no signup required.
Try the PDF CompressorWhy compress PDFs?
PDFs with embedded images — scanned documents, portfolios, brochures, reports — can easily reach 20–100MB. This causes problems: email attachments get rejected, file upload portals refuse them, and sharing via cloud links becomes slow and unwieldy.
PDF compression reduces the DPI of embedded images (the main source of large file sizes) without affecting text, links, or document structure. A 50MB brochure can often be compressed to under 5MB with no visible quality difference on screen.
Step-by-step: compress a PDF in seconds
Open the PDF Compressor
Visit the free PDF Compressor tool. No account, no installation, and no file size limits — everything runs in your browser.
Upload your PDF
Drag and drop your PDF onto the upload area, or click to browse. The file is loaded directly into your browser's memory.
Choose a compression level
Select Low, Medium, or High compression. Medium (around 72 DPI for images) is the best balance between quality and file size for most documents.
Download the compressed PDF
Click Compress PDF and download your smaller file. Compare the before and after file sizes — you'll typically see 40–80% reduction.
Pro tips for best results
Use Medium for most documents
High compression can make scanned documents hard to read. Medium compression cuts file size significantly while keeping text and images sharp enough for screen viewing.
Image-heavy PDFs compress most
PDFs with embedded photos see the largest reductions. Text-only PDFs are already small and won't compress dramatically.
Check the result before sending
After compressing, open the PDF and scroll through it. Verify signatures, charts, and photos are still clear before sharing with clients.
Compress before emailing
Most email providers cap attachments at 10–25MB. Compressing large reports, portfolios, or scanned documents beforehand avoids bounce-backs.
Your PDF never leaves your device
Unlike tools that upload your PDF to a cloud server, our compressor uses pdf-lib to process everything locally in your browser. Contracts, tax returns, medical records, and confidential business documents stay completely private.
Frequently asked questions
How much can a PDF be compressed?
It depends on the content. PDFs with large embedded images can be reduced by 70–80%. Text-heavy PDFs with no images may only compress 10–20% since text is already encoded efficiently.
Will compression make my PDF unreadable?
Not if you use Medium or Low compression. High compression reduces image DPI significantly, which can make scanned documents or photos look blurry. Use High only when file size is critical and image quality is secondary.
Does compressing a PDF affect text?
No — text is vector-based in PDFs and is not affected by compression. Only embedded raster images (photos, scans) are affected by quality settings.
Can I compress a password-protected PDF?
Password-protected PDFs cannot be compressed unless you first remove the password. Use the PDF Password tool to unlock the PDF, then compress it.
Is it safe to compress confidential PDFs online?
With our tool, yes — because the compression runs entirely in your browser using pdf-lib. Your PDF is never uploaded to any server, so confidential documents, contracts, and financial records stay completely private.