PDF Compressor

How to Compress a PDF

1. Upload PDF: Drag or click to select your PDF — supports files up to 100 MB for browser-based compression.
2. Choose compression level:
   • Low compression: Minimal quality reduction — best for print-quality output; 20–40% size reduction.
   • Medium compression: Good balance of quality and size — best for screen viewing and email; 40–70% reduction.
   • High compression: Maximum size reduction — best for archiving and upload portals; 70–90% reduction, some visible quality loss in images.
3. Preview before downloading: View the compressed PDF quality on-screen — verify text remains legible and images acceptable before committing.
4. Download compressed file: Save the optimized PDF — compare file sizes in the download confirmation to verify the reduction achieved.

Real-World Use Case

An immigration attorney needs to submit application packages to USCIS online portals with a strict 25 MB total limit per submission. A typical application includes scanned forms, identity documents, evidence letters, and supporting documents — often totaling 60–80 MB of scanned PDFs. After compressing each component PDF to medium compression, the package shrinks to 18 MB — well under the limit. Critically, all text remains fully legible (USCIS requires legible documents), and the attorney verifies each compressed PDF before submission. The compression reduces submission time and eliminates failed upload errors from oversized files.

Best Practices

• Compress scanned PDFs most aggressively: Scanned documents are image-heavy — high compression reduces file size by 70–90% while maintaining legibility for text-based content.
• Use medium compression for professional distribution: High compression degrades charts and photographs in reports — medium compression balances quality and size for client-facing documents.
• Always verify text legibility: Zoom to 100% in the compressed PDF preview and check small text (footnotes, captions) remains readable before submitting to portals.
• Compress before merging: Compress individual PDFs first, then merge — this gives maximum control over quality per document vs compressing the entire merged file.
• Use specific compression targets: Know your upload limit before compressing — target 50% under the limit for reliable submission (25 MB limit → target 12 MB or under).

Performance & Limits

• Maximum input size: Up to 100 MB PDF for browser-based compression.
• Typical compression ratios: Scanned image PDFs: 70–90% reduction; presentations with images: 40–60% reduction; text-only PDFs: 10–30% reduction.
• Processing speed: A 20 MB scanned PDF compresses in 5–15 seconds depending on page count and device.
• Text PDFs compress less: Text-based PDFs are already efficiently encoded — don't expect dramatic compression on native digital PDFs.
• Font embedding: Compressed PDFs retain embedded fonts for correct text rendering across all devices.

Common Mistakes to Avoid

• Using maximum compression on print-quality documents: Aggressive compression degrades photos and fine details below acceptable print quality — use medium or low compression for documents intended for printing.
• Compressing already-compressed PDFs: Re-compressing a previously compressed PDF yields diminishing returns and additional quality loss — check if the PDF was already optimized.
• Not checking the compressed file size: Verify the actual output file size before submitting — some PDFs don't compress significantly if they're already optimized.
• Overwriting the original: Always save the compressed version as a new file — keep the original for cases where higher quality is needed later.
• Ignoring text legibility in high compression: High compression can make small text illegible — always preview at 100% zoom before using compressed PDFs for legal or official submissions.

Privacy & Security

• Browser-local processing: PDF compression runs entirely in your browser — document contents never leave your device.
• Legal document safety: Compress confidential contracts, legal filings, and financial reports without content being exposed to third-party servers.
• No content modification: Compression reduces file size by optimizing image encoding and removing redundant data — document text and structure are preserved.
• No file retention: Uploaded PDFs are cleared from browser memory when you navigate away — no documents are stored between sessions.