Compress PDF
Reduce PDF file size for email, web upload, or storage without sacrificing readability. Choose from optimized presets (Screen, Web, Print) or fine-tune compression settings. Embedded images are re-encoded at your target quality — the single biggest size reduction for most PDFs. All compression happens locally for complete privacy.
What does this tool do?
The PDF Compressor reduces file size by optimizing the internal components of PDF documents. Most PDF bloat comes from unnecessarily high-resolution images embedded at print quality when only screen quality is needed. Our compressor analyzes your PDF's contents and applies intelligent compression to different element types. For images, it re-encodes them at your chosen quality level and DPI setting. For fonts, it subsets them to include only the characters actually used in the document. For metadata, it can strip hidden information that serves no visual purpose. The result is a significantly smaller file that looks visually identical to the original for its intended use case. Screen-optimized PDFs are typically 70-90% smaller than print-originals, making them suitable for email attachments, web uploads, and mobile viewing.
How it works
The compressor uses a multi-stage optimization pipeline. First, it analyzes the PDF structure to identify all embedded resources — images, fonts, metadata streams, and structural overhead. For images, it decompresses each embedded image, resamples it to the target DPI (150 for screen, 300 for print), and re-encodes it at the specified JPEG quality level (50% for screen, 85% for web, 95% for print). For fonts, it rebuilds font subsets containing only glyphs referenced in the text. The linearization process reorganizes the PDF structure so pages can render progressively as they download. Finally, the optimized document is assembled and offered for download. All processing uses MuPDF's compression engine running locally via WebAssembly.
Features
- Four intelligent presets: Screen (50%), Web (72%), Print (90%), and Custom
- Re-encodes embedded images at optimized quality/DPI settings
- Font subsetting removes unused characters to reduce file size
- Metadata stripping option removes hidden tracking information
- Linearization for faster web viewing of large documents
- Before/after size comparison to evaluate compression effectiveness
- Batch processing capability for multiple files
- Preserves text searchability and document structure
How to use
- 1
Upload your PDF file
Drag your PDF onto the drop zone or click to browse. The tool analyzes the file and displays its current size and page count. Typical candidates for compression are scanned documents, photo-heavy PDFs, and files created from high-resolution sources.
- 2
Select a compression preset
Choose the preset matching your intended use: 'Screen' for maximum compression (email, mobile viewing), 'Web' for balanced quality and size (website uploads), 'Print' for minimal compression (professional printing), or 'Custom' for manual control over all parameters.
- 3
Review advanced options (optional)
For custom mode or fine-tuning, adjust image quality percentage (lower = smaller file), target DPI (150 for screen, 300 for print), and enable/disable font subsetting and metadata removal. Most users get excellent results with presets alone.
- 4
Compress and compare
Click 'Compress PDF' and watch the progress indicator. When complete, you'll see before and after file sizes with the percentage reduction. A preview of the first page lets you verify quality is acceptable before downloading.
- 5
Download the optimized file
The compressed PDF downloads automatically. Open it to verify it meets your needs. If too much quality was lost, re-compress with a higher quality setting. If still too large, try the Screen preset or further reduce DPI.
Common use cases
Email attachments within size limits
Most email services have 10-25MB attachment limits. Compress large reports, presentations, and scanned documents to fit within these restrictions without splitting across multiple emails.
Faster web form uploads
Government portals, job applications, and insurance claim forms often limit upload sizes. Compress your supporting documents to meet these requirements while maintaining readability.
Mobile-friendly document sharing
Large PDFs consume excessive mobile data and storage. Compress files before sharing via messaging apps to ensure recipients can download and view them quickly even on limited data plans.
Cloud storage optimization
Free cloud storage tiers have limited space. Compressing PDFs before uploading lets you store more documents without upgrading to paid plans.
Print-ready files for professional printing
Uploading to print shops often has file size limits. The Print preset optimizes files for professional output while keeping them small enough for upload systems.
Tips & best practices
- Start with the Web preset (72% quality) — it provides excellent size reduction while maintaining visual quality for most documents
- Text-heavy PDFs may not compress significantly — focus compression efforts on image-heavy documents
- For scanned text documents, consider converting to searchable PDF first using OCR, then compress — text layers compress better than images
- Always keep your original file as a backup — compression is lossy for images and cannot be reversed