PDF files can grow huge fast — especially those with embedded images, scanned pages, or presentation exports. Most email servers cap attachments at 10–25 MB. Here's how to shrink your PDFs without sacrificing readability.
Why compress a PDF?
Large PDFs cause real problems: email rejections, upload failures on portals, slow downloads, and bloated storage. Compression typically cuts 50–80% of the file size with no visible difference to the reader. A 20 MB scanned document can become 3–4 MB — small enough for any email.
How PDF compression works
PDF compression works by re-encoding images inside the document (converting to a more efficient format, reducing DPI, or applying JPEG compression), removing redundant metadata, compressing embedded font data, and stripping out embedded page thumbnails. A scanned PDF is almost entirely images, so it benefits most. A text-only PDF may barely shrink at all.
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How much can you compress a PDF?
- Scanned documents (images only): typically 60–90% reduction
- Presentations with embedded photos: 40–70% reduction
- Mixed PDFs (text + images): 30–60% reduction
- Text-only PDFs: 10–30% reduction
- Already-compressed PDFs: minimal further reduction
Tips for getting the best results
- If you control the source file (Word doc, PowerPoint, Canva), export with 'optimize for web' or reduce image resolution to 150 DPI before creating the PDF
- For scanned documents, 150–200 DPI is enough for screen reading and most printers — you won't see a difference from 300 DPI
- Remove unnecessary pages before compressing — fewer pages means smaller output
- If the PDF was exported from Photoshop or Illustrator, re-export at a lower quality preset first, then compress
Frequently Asked Questions
Will compressing a PDF reduce text quality?
No — text in PDFs is stored as vector data, not images, and isn't affected by compression. Only embedded images get re-encoded.
Is the PDF compressor free?
Yes — completely free with no signup required. Files are processed entirely in your browser and never uploaded to any server.
Can I compress a scanned PDF?
Yes, and scanned PDFs see the biggest gains — typically 70–85% smaller — because the entire document is stored as images.
Is it safe to compress sensitive documents?
Yes. LoudHive processes everything locally in your browser. Your PDF never leaves your device.