How to compress a PDF
- Add your PDF by dropping it on the box or clicking to choose it.
- Choose a compression level. Recommended works for most files. Use Strong for photo-heavy PDFs and Extreme for scanned documents.
- Press Compress PDF and compare the before and after sizes.
- Download your smaller PDF.
How PDF compression works
In most large PDFs, the bulk of the file size comes from images — photos, scanned pages and screenshots embedded at much higher resolution than a screen or office printer needs. The Light, Recommended and Strong levels find every JPEG image inside the PDF, scale it down to a sensible resolution and re-encode it with efficient JPEG settings. Text, fonts, links and vector graphics are left untouched, so the document still looks sharp and text stays searchable and selectable.
The Extreme level takes a different approach: it renders each page as an image at 96 DPI and rebuilds the PDF from those images. This gives the biggest reduction for scanned documents, but the text becomes part of the image.
| Level | Image resolution | Best for |
|---|---|---|
| Light | up to 2400 px | Print-quality documents |
| Recommended | up to 1700 px | Email, sharing, most uploads |
| Strong | up to 1300 px | Strict upload limits |
| Extreme | 96 DPI pages | Scanned pages, smallest files |
Common size limits
- Gmail and Outlook attachments: 20–25 MB.
- Job and government portals often allow only 1–5 MB, sometimes 200–500 KB.
- Court e-filing systems and insurers frequently cap uploads at 10 MB per document.
If a PDF is still too large, try a stronger level, or split the PDF into smaller parts.
Why didn’t my PDF get smaller?
PDFs that contain mostly text and vector graphics (for example, documents exported from Word) are already compact — there is little to remove. If the result would be larger than the original, the tool keeps your original file. Scanned PDFs, on the other hand, usually shrink by 60–90% with the Extreme setting.
Private by design
Contracts, bank statements and ID documents should not be uploaded to unknown servers. This compressor runs entirely in your browser using the open-source pdf-lib and PDF.js libraries, so your document never leaves your device.
Frequently asked questions
Is it safe to compress confidential PDFs here?
Yes. The PDF is processed in your browser and is never uploaded.
Will compression reduce quality?
Images are re-encoded at a lower resolution, which is not noticeable on screen at the Recommended level. Text and vector graphics are not changed.
Can I compress a password-protected PDF?
Not directly. Open it, remove the password (for example by printing it to a new PDF), then compress it.
How can I compress a PDF to under 1 MB?
Try Strong first. If it is still too large and the PDF is scanned, use Extreme, which usually brings scans well under 1 MB.
Is there a file size limit?
No fixed limit. Very large PDFs (hundreds of MB) depend on your device’s memory.