Compress PDF Online — Reduce PDF File Size Free
Reduce PDF file size by optimizing images (Client-side processing)
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How It Works
Upload Your PDF
Select or drag your PDF file to compress
Choose Compression Level
Select your preferred compression intensity
Download Compressed PDF
Get your optimized PDF instantly
Help & Tips
- Images: Compression helps most on image‑heavy PDFs.
- Balance: Try medium quality for size vs. readability.
- Preview: Check pages to ensure text remains legible.
- Version: Newer PDF versions may compress more efficiently.
- Limits: Text‑only PDFs often see minimal gains.
Frequently Asked Questions
Is the PDF compressor free to use?
Yes. PDFLY's PDF compressor is completely free with no sign-up and no watermarks added.
How much can I reduce a PDF file size?
Results vary by file content. Image-heavy PDFs can be reduced by 50–80%. Text-only PDFs see minimal reduction as text is already compact.
Will compression reduce the quality of my PDF?
Compression reduces image resolution. Use Medium or Low compression to balance file size and quality. Use High compression only when file size is critical.
Are my files uploaded to a server when compressing?
No. PDF compression on PDFLY is done entirely in your browser. Your files never leave your device.
What DPI setting should I use?
Use 72 DPI for screen-only documents, 150 DPI for web sharing and 300 DPI if you need print-quality output.
Why Use PDFLY to Compress PDFs?
PDFLY's compression tool is ideal for reducing file sizes without sacrificing too much quality:
- Client-Side Compression: Files are compressed entirely in your browser — no uploads, no waiting for server processing.
- Adjustable Quality Settings: Choose High, Medium, or Low compression and set custom DPI to balance file size vs quality.
- Best for Image-Heavy PDFs: Scanned documents and PDFs with many photos can be reduced by 50-80% in size.
- No Watermarks: Compressed PDFs are delivered clean with no branding or watermarks added.
- Instant Results: Because compression happens in your browser, you get results in seconds with no upload time.
Supported Formats & Limitations
| Feature | Details |
|---|---|
| Input Format | PDF (standard, scanned, and native) |
| Output Format | PDF (compressed, smaller file size) |
| Maximum File Size | Browser-dependent (typically up to 500MB) |
| Compression Levels | High, Medium, Low (with custom DPI 72-300) |
| Processing Method | Client-side (browser-based, no upload) |
| Best Results | Image-heavy PDFs, scanned documents, photography PDFs |
Common Use Cases for PDF Compression
Reducing PDF file size is useful in many scenarios:
- Email Attachments: Compress large PDFs to stay under email attachment size limits (typically 25MB for Gmail).
- Web Uploads: Reduce file size before uploading to job application portals or form submissions with file size restrictions.
- Mobile Sharing: Compress PDFs before sharing via messaging apps or mobile data to save bandwidth.
- Cloud Storage: Reduce file sizes to save space in Google Drive, Dropbox, or OneDrive.
- Scanned Documents: Compress scanned receipts, invoices, and paperwork that contain large image files.