Shift · Guides

Compress a PDF without destroying readability

Updated 2026-08-06 · ~8 min read

Email gateways and government portals love to reject a 28 MB PDF. Blindly smashing quality to “low” can turn contracts into muddy gray soup. The goal is the smallest file that still reads cleanly at 100% zoom on a laptop and on a phone.

Diagnose what makes the file heavy

• Scanned pages — full-page images; OCR may help later, but size comes from pixels.
• Embedded images — screenshots at 300 DPI inside a slide deck.
• Unused fonts / duplicates — less common, but desktop exporters leave baggage.
• High-res vector + raster mixes — CAD exports and magazines.

A sane compression order

1. If you still have the source (DOCX, InDesign, Google Doc), export a cleaner PDF first — compression cannot invent sharp text from a blurry scan.
2. Open PDFShift and use compress for files that need a server-side pass.
3. Check a text-heavy page and a photo page after compression.
4. If text looks soft, try a milder setting or re-export at 150 DPI instead of 300 for on-screen reading.

Other PDF jobs on Shift

PDFShift also covers merge, split, rotate, and watermark in the browser, plus unlock/protect on the converter when needed. OCR belongs in OCRShift when you need selectable text from a scan — compression alone will not magically add a text layer.

Privacy notes

Merge/split/rotate/watermark stay local. Compress, unlock, and protect use the converter — treat them like any temporary upload: fine for most office docs, think twice for highly sensitive material unless your threat model allows it.