How to Reduce PDF File Size
Large PDF files are difficult to share, upload, and store. SublimePDF's compression tool can dramatically reduce file size while keeping text sharp and images clear.
Follow the step-by-step instructions below, then use the free tool directly — no registration or download required.
Open Tool →How to Reduce PDF File Size — Step by Step
Upload your PDF
Open the Compress PDF tool and add the file you want to reduce.
Choose quality level
Select Low (maximum compression), Medium (balanced), or High (minimal compression).
Download smaller file
See the before/after file size comparison and download your compressed PDF.
Pro Tips
- 💡 Image-heavy PDFs benefit most from compression
- 💡 Try 'Medium' quality first — it usually provides the best balance
- 💡 If the file is still too large, consider removing unnecessary pages first
Privacy & Security
All processing happens directly in your browser. Your files are never uploaded to any server — they remain on your device throughout the entire process. SublimePDF uses WebAssembly technology for fast, secure, client-side processing.
Works Everywhere
This tool works on any modern browser — Chrome, Firefox, Safari, or Edge — on desktop, tablet, or mobile. No software to install. PDF is an open ISO standard supported by all major platforms.
How to Reduce PDF File Size — FAQ
How much smaller will my PDF be?
Will text become blurry?
Related Guides
How to Compress PDF for Email
Email services typically limit attachments to 25MB. If your PDF is too large, SublimePDF can compress it dramatically while maintaining readable quality — perfect for sending via Gmail, Outlook, or any email service.
How to Optimize PDF For Web
PDFs published on websites need to load quickly for visitors and be lightweight enough for search engines to crawl efficiently. An unoptimized 20 MB PDF can take 30+ seconds to render in a browser, causing visitors to leave. Web optimization linearizes the PDF for progressive loading, strips unnecessary metadata, and compresses content so the first page appears almost instantly.
How to Compress Images In PDF
Image-heavy PDFs from design files, photo reports, and scanned documents can balloon to hundreds of megabytes, making them impossible to email or slow to load online. Compressing the embedded images is the most effective way to shrink these files because images account for 90%+ of the file size. SublimePDF recompresses every image in your PDF to your chosen quality level while keeping text and vectors untouched.