Compress PDF
Reduce PDF size while maintaining quality - 100% client-side
Reduce PDF file sizes significantly by optimizing images, subsetting fonts, and compressing object streams — without visibly degrading document quality. Everything runs locally in your browser.
PDF Compression Techniques: Images, Fonts, and Stream Encoding
PDF compression is a multi-layered process targeting the three main contributors to file size: raster images, embedded fonts, and content streams. Images are typically the largest component — a scanned page or high-resolution photo can consume several megabytes on its own. JPEG recompression with controlled quality settings, image downsampling for display-appropriate resolution, and converting RGB images to grayscale where color is unnecessary are the primary image-side levers.
Font embedding is another major contributor. PDFs routinely embed entire font files for the handful of characters actually used. Font subsetting retains only the glyph outlines actually present in the document, reducing a 300 KB font file to 20-50 KB. For documents using many different fonts across many pages, subsetting alone can cut file size by 30-50%.
Content streams — the instructions that describe page layout, text positioning, and drawing operations — are compressed using zlib/Deflate encoding by default, but some PDF generators leave these uncompressed. Our tool ensures all object streams are properly deflate-compressed and that unnecessary metadata, thumbnails, and duplicate objects are removed.
Lossless vs. Lossy PDF Compression: Choosing the Right Approach
Lossless compression (structure optimization, font subsetting, stream re-encoding) reduces file size without any degradation — the document is byte-for-byte equivalent in visual appearance and content to the original. Lossy compression involves resampling high-resolution images to lower DPI, applying higher JPEG compression ratios, or converting color images to grayscale — all of which produce smaller files but at the cost of some image quality. For most office documents and presentations, lossless compression alone achieves 20-40% reduction. For PDFs containing high-resolution photographs, lossy compression can deliver 60-80% reduction at quality settings that are imperceptible for on-screen viewing.
Reduce PDFs for email attachments
Shrink files to fit below email attachment limits (typically 10-25 MB) without asking recipients to use file transfer services.
Optimize PDFs for web delivery
Compress PDFs embedded in websites or downloadable from portals to improve page load times and reduce bandwidth costs.
Archive scanned documents efficiently
Reduce storage footprint of large scanned document archives while preserving visual quality for compliance and reference.
Compress presentation PDFs
Export-to-PDF presentations often include unoptimized images — compression makes them practical to share via messaging apps.
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Upload the PDF to compress
Select or drag in the PDF you want to reduce. The tool displays the original file size so you can compare against the compressed output.
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Choose compression quality
Select a compression level — from 'High Quality' (minimal compression, no visible change) to 'Maximum Compression' (significant size reduction with some image quality trade-off).
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Compress and compare sizes
Click Compress PDF to run optimization in your browser. The result shows both original and compressed sizes, plus the percentage reduction achieved.
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Download the optimized file
If satisfied with the size-to-quality ratio, download the compressed PDF. If you need more reduction, try a higher compression level.
Image downsampling and recompression
Reduces embedded image resolution to display-appropriate DPI and applies optimized JPEG encoding to dramatically shrink image-heavy PDFs.
Font subsetting
Strips unused glyphs from embedded fonts, keeping only what the document actually uses — a major size reducer for font-rich documents.
Multiple compression levels
Choose from several presets balancing file size and quality, from lossless structure optimization to aggressive lossy compression.
Before/after size reporting
Clear display of original size, compressed size, and reduction percentage so you can make an informed keep-or-retry decision.
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