Reduce PDF File Size: Scanned vs Text PDFs

“Already efficient” is usually honest

If FileShrinkr’s browser Compress PDF tool says it could not shrink further, the rebuild was not smaller than your upload. That often happens with:

• Text PDFs exported from Word, Google Docs, or LaTeX (efficient fonts + vectors)
• PDFs that were already compressed once by Acrobat, Preview, or another tool
• Short documents with little image content

Rasterizing every page to JPEG can increase size for those files—full-page photos of text are heavier than real text streams. FileShrinkr refuses to hand you a larger download; it keeps the original and tells you so.

Try the tool at /compress-pdf.

Scanned PDFs usually shrink

Phone scans, flatbed scans, and “camera PDF” apps store each page as a large embedded image (or several). Re-encoding those pages at a controlled width and JPEG quality is exactly what browser compressors are good at.

Typical wins:

• Multi-page ID / passport / form scans from a phone
• Photo-heavy slide decks exported to PDF
• Browser “Print to PDF” of image-heavy web pages

If your PDF looks like a stack of photos of paper, Compress PDF is the right tool. If it is a crisp Word export with selectable text, expect limited or zero savings in the browser.

Settings when you need more size reduction

Open Advanced Tuning on Compress PDF:

1. Drop JPEG quality toward 70% or 50% (Low).
2. Set max page width to 1280 or 960 px.
3. Keep render zoom moderate (100–150%). Extreme zoom (300–500%) improves detail for reading but works against size goals.
4. Optionally enable Retry stronger if needed for one automatic stronger pass.

Then compress again. Check the before/after stats. If you still see “already efficient,” the source is not a good candidate for raster recompression.

DPI, page size, and “looks blurry”

Lowering max width reduces pixels on each page. That is similar to lowering effective DPI for print—see image DPI and resolution. For on-screen review and email, 1280–1600 px wide pages are usually enough. For print shops or legal archives that need fine type, prefer higher width + higher JPEG quality—or keep the original PDF.

Remember: Compress PDF turns pages into images. Zooming the PDF viewer afterward cannot recover text sharpness the way a vector PDF can.

When to rebuild from images instead

If you still have the original JPGs/PNGs:

1. Compress the images first (target KB or quality slider).
2. Use Image to PDF / merge—see merge images into one PDF.

That path often beats compressing an already-baked PDF, because you control each photo before packaging.

Password and page limits

• Unlock password-protected PDFs before upload.
• FileShrinkr Compress PDF allows up to 50 MB and 500 pages in the browser. Very large books may need splitting or a desktop Ghostscript/pikepdf workflow.

Related reading

• How to compress a PDF online
• Compress PDF vs Image to PDF
• Prepare images for email
• FAQ