Compress a scanned PDF

Make a PDF smaller by re-encoding the images inside it, dropping duplicated objects and clearing metadata, without sending the document anywhere.

Drop your files here

.pdf · up to 300 MB

Choose files

How to Compress PDF

1
Drop your PDF
Add one file or up to twenty at once. Each document is opened by your own browser, so nothing is uploaded and nothing waits in a queue.
2
Pick a compression level
Best quality keeps images at 300 DPI and quality 85. Balanced goes to 150 DPI and quality 65. Smallest file drops to 96 DPI and quality 45. Or pick Target size with a goal such as 500 KB, and the quality and resolution are found for you.
3
Download the smaller file
The result keeps every page, all text and all form fields. Several files come back as one ZIP archive; each name ends in -compressed, or in the target, such as -500kb or -smallest, when you compress to a size.

A scan is a picture of every page

A scanned PDF stores an image of each sheet, not the letters on it, so its weight is the weight of those pictures. This page opens the compressor on Balanced: any page picture finer than 150 DPI is resampled to 150 DPI and saved as a JPEG at quality 65. A letter-size sheet scanned at 300 DPI, 2550 × 3300 pixels, comes back at 1275 × 1650, a quarter of the pixels. A scan made at 150 DPI or less keeps its pixels and is only re-encoded.

What changes and what stays

Pages keep their size on paper, their count and their order; only the density of the picture drops. Each picture is replaced only when the new copy is more than a tenth smaller, and if the whole file would come out larger, you get the original back. A searchable scan keeps its hidden OCR text as it was and stays searchable. In our check on October 20, 2026, a three-page grayscale scan at 200 DPI, 2.3 MB before, came down to 539 kB on the balanced level, a 77 percent drop. The close-up under the preview shows the same patch of a page before and after at 100 %, for checking small print.

Black-and-white scans and OCR

Pages scanned in pure black and white, one bit per pixel, are already compact, often stored with fax-style CCITT or JBIG2 compression. The compressor leaves them as they are, along with pictures saved as JPEG 2000, so such a scan barely shrinks. Compression also does not make a scan searchable. If you need to find, select or copy the words, run OCR PDF first, on the full-resolution original, which gives text recognition more to work with than a 150 DPI copy. OCR PDF runs on our server, and its “What's next?” row brings the searchable file back to Compress PDF.

Scans from a phone

The compressor runs in the phone's browser, so a scanned passport or bank statement stays on the device. For black text on white paper, “Turn images to grayscale” under “More settings” removes the color from the page pictures; leave it off when a blue signature or a red stamp has to keep its color. A long color scan can run an older phone out of memory; the page then says so and offers Split PDF to compress it in parts. On an iPhone the download opens the Share sheet; Android saves the file to Downloads.

The document never leaves your computer

Compression runs inside your browser tab, in a background thread on your own machine. The PDF is not uploaded, not copied to a server and not stored anywhere for us to delete later, which is why contracts, payslips and medical scans can be compressed here. Close the tab and everything still in memory is gone with it.

Frequently asked questions

Why did my PDF barely get smaller?

Because it has little or no raster content. Text, fonts and vector graphics are already compressed inside a PDF and are copied over untouched, so a file of pure text has almost nothing left to squeeze. Files built from scans or photographs shrink the most.

What is the difference between the three levels?

They set two numbers: JPEG quality and the resolution ceiling. Best quality uses quality 85 and 300 DPI, Balanced uses 65 and 150 DPI, Smallest file uses 45 and 96 DPI. Lower numbers mean smaller files and softer images; page count and text are identical in all three.

Will my scanned pages look worse?

At Balanced and Best quality, scanned text stays sharp enough to read comfortably on screen and to print. At Smallest file, photographs and colour gradients show visible artefacts and fine print softens. Try Balanced first and compare before you commit to a harsher setting.

Does my file get uploaded to a server?

No. The document is parsed, re-encoded and rebuilt by your own browser. No part of it travels over the network, and nothing of yours is stored anywhere. Compression also works with the connection switched off once the engine has loaded, which happens with the first file you add.

Is the text layer still searchable afterwards?

Yes. Text is never rasterised here, so every word stays selectable, searchable and copyable, and bookmarks, links and form fields keep working. Only the embedded images are re-encoded, which is what makes the file smaller in the first place.

Why can a password-protected PDF not be compressed?

Because its contents are encrypted, and the images cannot be read without the password. Remove the protection first with the password removal tool, compress the plain file, then apply a password again if you still need one.

How small can a vector or text-only document get?

Usually a few percent at best. Such a file is mostly font data and drawing instructions, both already packed by the format itself. When there is nothing raster to work on, the tool says so plainly instead of handing back a file of the same size.

Can I compress several PDFs at once?

Yes, up to twenty files in one go, with the same level applied to each. Every document is processed separately in your browser and the results arrive together in one ZIP archive, with each file keeping its original name plus a suffix: -compressed for a level, or the target, such as -500kb, when you compress to a size.