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By PDFWix Editorial Team · March 2026
Five techniques to shrink any PDF without visible quality loss — from one-click browser compression to advanced optimisation, with honest trade-offs.
Almost every oversized PDF is bloated by one of three culprits: high-resolution scans (often 600 DPI when 150 will do), embedded full font families, and metadata left over from authoring software.
A 200-page contract scanned at 600 DPI in colour can balloon to 250 MB. Re-encoded with the right settings, it drops to 8 MB — small enough to email, with text that's still crisp on screen.
PDFWix's Compress PDF tool runs entirely in your browser. Drop the file, pick 'Recommended', and you'll typically see a 60–80% size reduction with no visible quality loss. Open PDFWix Compress PDF to try it on your own file, or follow our step-by-step guide to compress PDF on Mac using the same browser-based workflow.
PDFWix uses <a href='https://www.ghostscript.com' rel='noopener' target='_blank'>Ghostscript</a> — the open-source PDF engine used in professional publishing pipelines worldwide — to handle compression.
| File type | Original size | Recommended | High | Size reduction |
|---|---|---|---|---|
| Scanned contract (300 DPI) | 8.2 MB | 1.4 MB | 0.6 MB | 83-93% |
| Photo-heavy presentation | 12.1 MB | 2.8 MB | 1.1 MB | 77-91% |
| Text-heavy report (100 pages) | 4.4 MB | 3.8 MB | 3.1 MB | 14-30% |
| Mixed content (text + images) | 6.3 MB | 1.9 MB | 0.8 MB | 70-87% |
| Scanned ID document (600 DPI) | 3.1 MB | 0.4 MB | 0.18 MB | 87-94% |
| Office-created PDF (no images) | 0.9 MB | 0.8 MB | 0.7 MB | 11-22% |
Tested June 2026 using PDFWix Compress PDF with Ghostscript WebAssembly engine. Results vary by source content — scanned documents (image-heavy) compress more aggressively than text-based PDFs. Recommended level targets 150 DPI for images; High level targets 72 DPI.
| Scenario | Why compression is limited |
|---|---|
| Already compressed PDF | Prior compression removed recoverable data |
| Text-only PDF (no images) | Only 10-25% size reduction typical |
| PDF/A archival format | Encryption/metadata restrictions limit compression |
| Short scanned document (1-2 pages) | Minimum file overhead dominates |
If your PDF won't compress below a government portal's size limit (common with 100KB limits for UPSC, SSC, and passport applications), see our guide: Compress PDF to 100KB for Government Forms.
If you need pixel-level control, use the Advanced mode to set image DPI, JPEG quality and colour space. 150 DPI / Q70 / sRGB is the sweet spot for screen viewing.
For documents that mix screenshots and photos, downsample photos to 150 DPI but keep screenshots at original resolution — text inside screenshots gets blurry fast when downsampled.
Most PDFs embed entire fonts even when only a handful of glyphs are used. Subsetting keeps just the characters that actually appear, often saving 30-50 KB per font.
Subsetting is automatic in our Compress tool. If you're authoring the PDF, set your tool's 'Embed font subset' option (it's the default in Word, Pages, and InDesign).
PDFs accumulate cruft: thumbnails, comments from drafts, JavaScript hooks, embedded files. Run a 'PDF optimizer' pass (built into Compress PDF) to garbage-collect everything not referenced from a visible page.
Bonus: stripping metadata also removes the author name, original file path, and software version from your file — useful before sharing externally.
If the file is destined for archival, convert to PDF/A-2b. The format requires embedded fonts but standardizes encoding, which paradoxically makes the file smaller for many documents.
Pure lossless compression of an already-optimized PDF rarely yields more than 5%. The real wins come from re-encoding images (which is technically lossy but invisible at sensible settings).
If you absolutely cannot tolerate any image re-encoding — a contract with a stamp that must be byte-identical, for instance — limit yourself to font subsetting and metadata stripping. Expect modest size reductions.
Visibly, no — at the Recommended preset. Image data is technically re-encoded, but the result is indistinguishable from the original on a typical screen. For print, use Low.
Typical 50–80% reduction. Image-heavy PDFs (scans, photos) compress most. Text-only PDFs that already use minimal images gain less.
No — you need to unlock the PDF first with your password. Use Unlock PDF, then run compression.