Compress PDF files
Shrink scans and image-heavy PDFs with three presets. Text stays searchable, nothing is uploaded.
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How to compress PDF files
Add your files
Drop files on the box, paste them or choose them from your device. Nothing is uploaded.
Check the settings
The default preset suits most files. Change quality, size or format if you need a smaller file.
Download the result
Save each file or all of them as one ZIP. If a file cannot get smaller, you keep the original.
What makes a PDF large
A PDF is a collection of objects: page descriptions, fonts, images, form fields, bookmarks and metadata, most of them stored as compressed streams. Text and vector drawings are tiny; a 100-page contract with only text is often well under 1 MB. When a PDF runs to tens of megabytes, the cause is almost always one of these:
- Photos at full camera resolution. A 12-megapixel photo placed at the size of a postcard still keeps all 12 million pixels inside the file.
- Scans. Every page of a scanned document is one big image. A color A4 page at 300 DPI is 2480 × 3508 pixels, and many scanner apps store it with light compression.
- Images stored losslessly. Some programs save photos with Flate (lossless) compression instead of JPEG, which can make them several times larger.
- Duplicates and leftovers. The same logo embedded on every page, page thumbnails, editing data from the authoring program, and unused objects left over after edits.
How the PDF compressor works
The tool opens the PDF in your browser and rebuilds it. Text stays real text, so you can still select, search and copy it; pages are never turned into pictures. The work is done on the images and the structure of the file:
- Images that are larger than needed for their size on the page are downscaled to the chosen resolution, measured in DPI (dots per inch on the printed page).
- JPEG images are re-encoded at the chosen quality; losslessly stored photos and scans are converted to JPEG when that at least halves their size. CMYK, JPEG 2000 and JBIG2 images are left as they are.
- Duplicate streams are merged, unused objects and thumbnails are removed, and the file is saved with compact object streams.
Links, bookmarks and form fields are kept.
Choosing a preset
| Preset | What it does | Use it for |
|---|---|---|
| Light | Lossless clean-up only: no image is changed | Contracts, invoices and forms that must stay exactly as they are |
| Recommended | Images limited to 150 DPI, JPEG quality 75 | Email attachments, portals, reading on screens, office printing |
| Strong | Images limited to 96 DPI, JPEG quality 60 | Hard upload limits, scans you only need to read on screen |
| Custom | Your own DPI (72–300) and quality (30–95) | Special requirements |
The arithmetic behind the DPI numbers: an A4 page at 300 DPI needs 8.7 million pixels for a full-page image, at 150 DPI only 2.2 million, a quarter as many. On a laptop or phone screen, 150 DPI is still sharper than the display can show at full-page view, and office printers rarely benefit from more. For professional printing, keep the original.
How much a PDF shrinks depends entirely on its content. A scan or a brochure full of photos can become many times smaller; a text-only PDF that was saved efficiently has little left to remove, and in that case the tool keeps your original.
Common problems
- Still too big for an email after Strong. Split the PDF into parts, or check whether the size comes from embedded video, attachments inside the PDF or huge fonts, which image compression cannot touch.
- Scanned text looks blurry. Use Recommended instead of Strong, or rescan in grayscale at 200–300 DPI; black-and-white text compresses far better than a color scan of white paper.
- A signed PDF. Rewriting a digitally signed document invalidates the signature. Compress before signing, or send the signed original.
- PDF/A archives. Archival PDFs have strict rules; a compressed copy may no longer validate as PDF/A, so keep the original for official archiving.
PDF questions
Will the text in my PDF still be searchable?
Yes. Text is not touched, so it stays selectable and searchable. A scanned PDF only has searchable text if it was run through OCR before.
Why is my scanned PDF so large?
Each page is a full-page image, often in color at 300 DPI or more. The Recommended preset reduces those images to 150 DPI, which is usually the biggest single saving.
Can I compress a password-protected PDF?
No, nor PDFs that open freely but restrict printing or editing; the tool shows a message. Save an unprotected copy if you are allowed to, compress that, and protect the result again if needed.
Is the Light preset really lossless?
Yes. It only removes redundant data and repacks the file; every picture keeps exactly the same pixels.
What size should a PDF be for an email or job portal?
Job and government portals often allow only a few megabytes per file, while email services allow 20–25 MB per message. Our page on file size limits lists the main services.
Related tools
For Word, Excel and PowerPoint files use the Word, Excel and PowerPoint compressors, or go to the document compressor. How it works explains why your documents never leave your computer.