Removes redundant objects and compresses the PDF structure. Best results on unoptimized PDFs.
How it works
The PDF Optimizer reduces the file size of a PDF by applying a combination of compression techniques: resampling embedded images to lower DPI, re-encoding images as JPEG or WebP, compressing content streams, subsetting embedded fonts, and removing redundant objects. Use it before emailing, uploading to web forms, or archiving PDFs.
Email providers limit attachments to 10–25MB. Web form upload fields cap PDFs at 5–10MB. A typical 50-page report with full-resolution embedded photos can be 20–50MB. This tool compresses it to under 5MB with minimal visible quality loss.
How to use it: upload your PDF. Select an optimization profile: - Screen (72 DPI images): smallest output, suitable for email and web embedding - Web (96–150 DPI images): good quality for reading on screen - Print (300 DPI): slight compression, print-quality output - Custom: set image DPI, quality, and object compression manually
The original file and optimized file are shown with a size comparison and estimated reduction percentage before downloading.
What is compressed: embedded images (resampled and re-encoded), content streams (zlib compressed), embedded font subsets (unused glyphs removed). What is not compressed: already-optimized content, document structure required for PDF compliance.
Privacy: optimization runs in the browser. Your PDF is never uploaded.
Frequently Asked Questions
- A PDF with high-resolution photos at 300+ DPI reduced to 150 DPI Screen profile typically achieves 50–80% file size reduction. Text-only PDFs or PDFs with already-compressed images at appropriate DPI may see only 5–15% reduction. The tool shows the estimated reduction before you commit to downloading.
- No. Text in PDF is stored as vector outlines — it is resolution-independent and is never resampled. Only embedded raster images are resampled. Text, lines, and vector graphics remain sharp regardless of the DPI setting.
- Font subsetting removes unused glyph data from embedded fonts — keeping only the characters actually used in the document. A full Latin font may be 500KB; the subset with only the characters in the document may be 50KB. Enable subsetting for all shared/distributed PDFs. Only disable it if you need the full font for later editing.
- No. Decrypt the PDF first using the Remove PDF Password tool. Optimization requires read access to all content streams.