Free Online PDF Compressor — Reduce Any PDF to Your Target Size
Compress PDF files from megabytes to kilobytes directly in your browser. Set a target file size or use the quality slider — this tool re-renders every page for real, aggressive compression without any server upload.
Compress Your PDF File
How to Use This PDF Compressor
Select Your PDF File
Click the upload area or drag and drop your PDF file into the tool.
Choose Compression Level
Use the quality slider or click a preset guide card to automatically set the best quality and scale.
Click Compress PDF
Press the Compress PDF button. The tool re-renders every page and rebuilds the PDF in your browser.
Review Results
Check original size, compressed size, and percentage reduction in the results panel.
Download Compressed File
Enter an optional filename and click Download to save your smaller PDF.
Key Features
100% Free, No Limits
Compress unlimited PDFs without charges or daily caps.
Adjustable Quality Slider
Fine-tune JPEG quality from 10% to 95% and resolution from 0.5x to 3.0x.
Complete Privacy
Your PDF never leaves your device. Zero uploads, zero data collection.
Smart Preset Guide
One-click presets for normal docs, portal uploads, photos, and print quality.
No Signup Required
Start compressing immediately with zero registration.
All Devices & Browsers
Works on Chrome, Firefox, Safari, Edge — Android, iPhone, iPad, desktop.
How PDF Compression Works
Reduction % = ((Original − Compressed) ÷ Original) × 100Compression Process
- Page Rendering: Each page is rendered onto HTML5 Canvas at your chosen resolution scale.
- JPEG Encoding: Canvas is exported as JPEG at your chosen quality level.
- PDF Rebuilding: A valid PDF is constructed embedding each compressed JPEG as a page.
- Target Size Mode: Auto-calculates optimal quality when target size is set.
- Binary Assembly: Final PDF uses Uint8Array bytes for compatibility with all viewers.
Example: A 4 MB PDF with 12 pages at 60% quality, 1.5x resolution → each page ~60-80 KB → final PDF ~720-960 KB.
Note: Compression depends on content. Text compresses more than photographs. Resolution scale multiplies pixel dimensions directly.
Practical Examples
4 MB Assignment → 450 KB
Settings: Quality 40%, Scale 1.2
Result: 89% reduction
Use: University portal with 500 KB limit
8 MB Invoice Bundle → 980 KB
Settings: Quality 55%, Scale 1.5
Result: 88% reduction
Use: Email with 1 MB attachment limit
12 MB Scanned Docs → 1.4 MB
Settings: Quality 60%, Scale 1.5
Result: 88% reduction
Use: Recruitment portal upload
15 MB Brochure → 1.8 MB
Settings: Quality 55%, Scale 1.5
Result: 88% reduction
Use: Website download optimization
What Is a PDF Compressor?
A PDF compressor reduces file size by re-rendering each page as a compressed JPEG image — a technique called rasterization-based compression. This achieves 70-95% reduction on almost any PDF.
Designed for students, professionals, accountants, and anyone needing smaller PDFs quickly and privately. The trade-off is image-based pages (no selectable text). For selectable text, use Adobe Acrobat Pro.
Methodology
Uses browser PDF rendering + HTML5 Canvas JPEG encoder. Output follows PDF 1.4 spec with DCTDecode image XObjects. Binary constructed via Uint8Array for universal viewer compatibility.
Frequently Asked Questions
Yes, 100% free with no hidden charges, no signup, and no daily limits.
Your files never leave your device. All processing happens in your browser. No data is uploaded or shared.
Yes, set quality to 30-45% with scale 1.0-1.2. A 4 MB doc with 10-15 pages typically compresses to 300-600 KB.
Yes, pages become images. Text won't be selectable but will look identical. For selectable text, use Adobe Acrobat.
📄 Balanced (60%) for everyday docs. 📦 Max Compression (30%) for strict size limits. 📸 High Quality (80%) for photo PDFs. ✨ Near Original (92%) for print quality.
Depends on device memory. Smartphones: 20-30 MB. Desktops: 50-100 MB. Close other tabs for large files.
No, remove password protection first, then compress.
10% = maximum compression, visible quality loss. 90% = near-original quality, less reduction. 50-70% = best balance.
Yes, scanned PDFs compress very well — often 50-80% reduction since they're already image-based.