Five techniques to shrink any PDF without visible quality loss — from one-click browser compression to advanced print-shop 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.
The Recommended preset re-encodes images at ~150 DPI JPEG quality 70 — the sweet spot for screen viewing. The High preset pushes to ~96 DPI for the smallest possible file, with mild visible compression. The Low preset keeps images at their original resolution and is the right choice for files headed to a commercial printer.
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.