Compress PDF
Shrink a scanned or image-heavy PDF for email or an upload form, with text kept sharp.
Runs in your browser. Your file is never uploaded.
Before After
How this PDF compressor works
Nearly all of a large PDF is images. A page scanned in colour at 300 dpi weighs 1 to 5 MB, while the text on a page takes a few kilobytes. So this tool looks at every image, works out the size it is actually drawn at on the page, and if it holds more detail than the level you chose, scales it down and saves it as a JPEG. A 300 dpi scan reduced to 150 dpi keeps a quarter of its pixels and typically ends up 70 to 85% smaller.
Everything that is not an image — text, fonts, vector drawings, links, bookmarks and form fields — is kept exactly as it was. The file is also re-saved with compressed object streams, and objects nothing refers to any more (left behind by repeated editing) are dropped.
Choosing a level
- Light, 200 dpi: for files you may print. The smallest saving.
- Recommended, 150 dpi: scanned text stays crisp on any screen. Right for email and most forms.
- Strong, 100 dpi: the smallest file, for portals capped at 1 or 2 MB. Fine print in scans may soften.
After compressing, the page holding the most-reduced image is shown before and after, so you can check that small print is still readable before sending.
What it leaves alone
To avoid changing how anything looks, some images are deliberately not touched: images with transparency (common in logos and PNG screenshots), images in CMYK or other print colour spaces, JPEG 2000 and black-and-white fax-style images (already compact), masks, and images drawn inside patterns. A browser cannot re-encode these faithfully. If your PDF is mostly one of those, or mostly text, it may not get much smaller — the tool says so, and you keep your original. Embedded fonts are not subset or removed either.
Other ways to make a PDF smaller
Sending fewer pages is the one size cut with no quality cost: remove pages you do not need, or split the file to get under an email limit. Our guide on how to make a PDF smaller covers Preview, Word, Acrobat, Ghostscript and better scan settings.
Frequently asked questions
Is my PDF uploaded to compress it?
No. The file is read, compressed and saved inside your browser tab, and nothing is sent to a server. That is unusual for a PDF compressor — most upload the file — and it matters for the documents people most often need to shrink: scanned IDs, statements, contracts and application forms.
How much smaller will my PDF get?
It depends on what is in it. Scanned documents and PDFs full of photos usually shrink by 50 to 90%, because their images are stored at far more resolution than a screen needs. A PDF of mostly text exported from Word is already small, and may get only a few percent smaller or not shrink at all — the tool tells you when that happens, so you can keep the original.
Does compressing a PDF reduce quality?
Only for images, and only for images stored above the level you pick. Text, fonts, vector drawings, links and form fields are left exactly as they were and stay sharp at any zoom. Recommended (150 dpi) keeps scanned text easily readable on screen; use Light (200 dpi) if the file will be printed, and Strong (100 dpi) for portals with a tight size limit.
Why did some images stay the same?
Images with transparency, CMYK or other print colour spaces, JPEG 2000 encoding, or masks are left untouched, because a browser cannot re-encode them without changing how they look. Images that are already at or below the chosen resolution are kept too. The result tells you how many were left alone and why.
How do I get a PDF under 1 MB or 2 MB?
Try Recommended first, then Strong. If a scanned file is still too large, remove pages that are not needed with Remove Pages from PDF, or split it into parts. For future scans, scanning in grayscale at 150 to 200 dpi gives a far smaller file than colour at 300 dpi.
Can I compress a password-protected PDF?
Yes. Enter its password when asked; the file is decrypted in your browser. The compressed copy is saved without a password, so if it needs one, add it again afterwards with Protect PDF.