Softonic

Compress PDF

Step 1 / 4 PDF compressor

PDFs get big when they contain scanned pages, photos, charts or exported artwork. This compressor works in your browser: it renders each page, saves that page as a JPEG at your chosen quality and render scale, then builds a new PDF from those compressed page images. It is best for scans and image-heavy PDFs; text stays readable, but it becomes part of the page image rather than selectable text.

How PDF compression works

  1. 1

    Upload the PDF

    Choose a PDF up to the tool limit; the compression work happens in your browser.

  2. 2

    Pick a preset

    Smallest file, balanced or higher quality set practical JPEG quality and render-scale defaults.

  3. 3

    Tune quality and scale

    Lower JPEG quality and render scale make smaller files; higher values keep pages sharper.

  4. 4

    Render each page

    Every page is drawn to an image, so complex layouts, scans and photos are flattened consistently.

  5. 5

    Build a new PDF

    The compressed page images are packed into a fresh PDF for download.

  6. 6

    Compare sizes

    Review the original and compressed sizes before saving or sharing the result.

Typical compression results

PDF type Before After (balanced) What to expect
Scanned contract (300 dpi) 25 MB 4-8 MB Large savings
Photo-heavy catalogue 40 MB 10-15 MB Large savings
Report with text and charts 8 MB 3-5 MB Moderate savings
Slide deck exported as PDF 18 MB 6-10 MB Good savings if images dominate
Simple born-digital invoice 200 KB May stay similar or grow Often not worth compressing

Scanned and image-heavy PDFs usually shrink the most. Simple text PDFs exported directly from Word, Google Docs, InDesign or a browser are already efficient, and because this tool flattens pages into images, very small text-only PDFs can become larger.

Quality settings, explained

  • Smallest file: JPEG quality around 55 and 1x render scale. Best when the upload limit matters more than sharpness.
  • Balanced: JPEG quality around 75 and 1.5x render scale. A practical default for scanned documents, reports and image PDFs.
  • Higher quality: JPEG quality around 90 and 2x render scale. Keeps pages sharper, but the output file is larger.
  • Manual tuning: Lower the quality first for smaller files. Lower the render scale only when the text still remains readable.

What changes in the PDF

  • Pages are flattened. Each page becomes a compressed JPEG image inside a new PDF.
  • Scans and photos shrink. Large raster images usually benefit most from JPEG compression.
  • Text remains visible but not selectable. Search, copy/paste and screen-reader structure may be lost in the compressed copy.
  • Interactive elements are not preserved as live fields. Forms, annotations, bookmarks, layers and digital signatures can be flattened or omitted.
  • Layout is kept visually. The new PDF should look like the original page, but it is a visual copy rather than the same internal document structure.

Tips for email and upload limits

Target Typical PDF limit
Gmail attachment 25 MB
Outlook.com attachment 25 MB
LinkedIn message attachment 20 MB on desktop, 10 MB on mobile
Most web upload forms 10-25 MB (varies)
WhatsApp document 2 GB

Compressing to 5 MB or less gives a comfortable margin for email, application forms and mobile sharing. WhatsApp allows much larger documents, but smaller PDFs still upload faster and use less data.

When not to compress

  • Archival copies. Keep the original file and compress only a sharing copy.
  • Print-ready PDFs. Press files should not be re-rendered; keep the source or export settings used by the printer.
  • Signed, fillable or accessible PDFs. Compression may flatten signatures, form fields, tags and selectable text.
  • Evidence or records. If the exact pixels or document structure matter, keep an untouched copy of record.

Frequently Asked Questions

It should stay readable at balanced or higher quality, but the output is image-based. If small text looks soft, increase the render scale or JPEG quality and compress again.

Balanced is usually the best first try. It often cuts image-heavy PDFs enough for email while keeping pages clear. Use smallest file only when the PDF still exceeds the limit.

No. This tool creates a visual, flattened PDF. Text, form fields, annotations, bookmarks and signatures may no longer behave as live PDF objects in the compressed copy.

Yes, but expect diminishing returns. Recompressing JPEG-based pages can reduce quality more than size. Start from the original PDF whenever possible.

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