Compress PDF Online
Reduce PDF file size without sacrificing crisp vector drawings. Downsamples heavy embedded images, cleans metadata, and re-compresses streams with zero disk retention.
Select PDF Document to Compress
Upload large architectural drawings, scanned sets, or multi-page documents
How to Compress PDF Files in 3 Steps
Quick, private, and vector-safe compression in volatile memory.
Upload PDF File
Select your PDF document. Files are buffered in encrypted volatile RAM without disk storage.
Select Compression Tier
Choose between Mild, Recommended, or High based on your desired DPI and size requirements.
Download Compact PDF
Receive your optimized PDF with immediate download and real-time percentage savings statistics.
PDF Compression Levels Comparison
Detailed breakdown of raster downsampling and stream optimization per tier.
| Compression Tier | Target Resolution (DPI) | Image Encoding | Vector Lines & Fonts | Average Reduction |
|---|---|---|---|---|
| Low (Mild) | Max 1600 px (~250–300 DPI) | High-fidelity JPEG (Q=0.85) | 100% Uncompressed Lossless | 15% – 30% |
| Medium (Recommended) | Max 1200 px (~150 DPI) | Balanced JPEG (Q=0.70) | 100% Uncompressed Lossless | 40% – 65% |
| High (Extreme) | Max 800 px (~96 DPI) | Compressed JPEG (Q=0.50) | 100% Uncompressed Lossless | 65% – 85% |
| Structure Optimization | Stripped metadata streams & unused object references across all tiers | Flate Deflate Re-encoding | Preserves PDF/A & rotation flags | Additional 5% overhead saved |
Frequently Asked Questions
How does CADConvert compress PDF files without losing vector sharpness?
Our engine selectively targets high-resolution embedded raster photographs and underlays for downsampling and JPEG recompression, while leaving all mathematical vector line work, curves, and text completely lossless.
What are the three compression levels?
Mild (Low) retains maximum raster resolution for high-end plotting; Recommended (Medium) downsamples images to 150 DPI for general emailing and web display (~50% size savings); Extreme (High) aggressively compresses to 96 DPI for minimum file size (~75% savings).
Is my PDF uploaded to permanent storage?
No. The optimization is executed 100% in volatile server memory (RAM) and immediately streamed back. No files or document metadata are saved to disk.
Can I compress architectural blueprints or CAD-generated PDFs?
Yes! The engine was specifically designed for architectural drawings and engineering documents, ensuring title blocks, thin lineweights, and text remain sharp.