Compress PDF Files Online for Free

Compress a PDF when it is too big to email, upload to a form, or keep on a full phone. This free PDF compressor rewrites the file with Ghostscript on our server: it scales down large images, keeps only the font characters the document uses, and drops data a reader does not need.

You pick one of three levels, and the tool shows an estimated size for each before you start. No account is needed and nothing is stamped on your pages.

How to compress a PDF online

1. Click Choose Files or drag one or more PDFs onto the page. Each file can be up to 25 MB.
2. Add more files or rotate pages if you need to, then click Choose Compression.
3. Pick Light, Recommended or Max compression. Each option shows an estimated new size.
4. Click Compress PDF, then download your smaller file. Several files come back together in one ZIP.

The estimates are a rough guide, not a promise. For our sample the screen estimated about 1 MB at Recommended, and the real result was 379.2 KB.

Which compression level should you choose?

Each level starts from one of the presets of Ghostscript's pdfwrite device and then sets its own image resolution. Images above that resolution are scaled down and stored again. Text and vector drawings stay sharp at every level, because they are not pictures.

Light compression for print and fine detail

Light uses the prepress preset and scales images down to 200 dpi. Choose it for documents you will print, scans with small handwriting, or photos you want to keep crisp. It saves the least space.

Recommended compression for email and screens

Recommended is the default. It uses the ebook preset and scales images to between 110 and 150 dpi, depending on the file size (130 dpi for files between 1 MB and about 4.7 MB). Pages still read well on a laptop or phone, and this is the level we used in our test.

Max compression for upload limits

Max uses the screen preset and scales images to 72 dpi, so it gives the smallest file. Use it when a portal rejects anything bigger. Zoom in on small print in scanned pages before you send the result, because fine details can blur at this level.

What makes a PDF file large?

Pictures are usually the heaviest part of a PDF. A scanned page or a photo saved at 300 dpi or more carries far more pixels than a screen can show, so lowering the resolution saves the most space.

Fonts come next. The compressor keeps only the characters your document uses from each embedded font, and it stores an image that appears several times only once.

A PDF that is mostly typed text is often small already. If the compressed copy is not smaller than your file, the tool gives you your original back and tells you the PDF is already optimized, so you never download a bigger file.

What happened when we tested Compress PDF

We used our own test file, sample-screenshots.pdf: a 12-page PDF of screenshots of our tools, 3.1 MB in size. At the default Recommended level the tool returned sample-screenshots_compressed.pdf at 379.2 KB, still 12 pages, and the results screen reported it as 88% smaller.

The level screen had estimated about 1 MB for Recommended, so the real file came out well under its own estimate. Tested in October 2026.

How to get a PDF under a file size limit

Email is the most common reason to compress. A personal Gmail account can send attachments up to 25 MB, and anything larger is turned into a Google Drive link instead. Other mail services and company servers set their own limits.

Upload forms are stricter. For the usual targets, see our guides to compressing a PDF to under 5 MB, getting a PDF down to 500 KB, compressing a PDF for job application portals and shrinking a scanned PDF for court e-filing.

If Max compression is still too big, convert color scans to grayscale with Grayscale PDF, or cut the document into parts with Split PDF and compress each part. You can join the parts again later with Merge PDF.

What this PDF compressor cannot do

A PDF that needs a password to open cannot be compressed until the password is removed, for example with Unlock PDF if you know it. A PDF that only restricts printing or copying is compressed normally, and the compressed copy no longer carries those restrictions.

Form fields do not survive. Compression turns them into fixed page content, so fill in a form before you compress it.

Every level converts colors to RGB. If a print shop asked for a CMYK file, send them the original instead of the compressed copy.

Your files are uploaded over HTTPS and deleted automatically within two hours. If a document must not leave your computer, read how to compress a PDF without uploading it, and on a school or work laptop see compressing a PDF on a Chromebook.

Frequently Asked Questions about Compress PDF

Does compressing a PDF lower its quality?

Only for images. Pictures above the level's resolution are scaled down and stored again, while text and vector graphics stay exactly as sharp as before.

Can I compress several PDFs at once?

Yes. Add as many PDFs as you like, each up to 25 MB, and they all use the level you pick. You download them together in one ZIP.

Why did my PDF not get smaller?

It was already compact, which is common for text-only files. In that case the tool returns your original file and says it is already optimized, instead of giving you a larger copy.

Can I compress a password-protected PDF?

Yes, if it opens without a password and only restricts printing or copying. A PDF that asks for a password when you open it must be unlocked first.

Do links still work after compression?

Yes. Links are kept at every level. Form fields are not: they become fixed page content.

Does the compressed PDF have a watermark?

No. The tool adds nothing to your pages, at any level.

How long do you keep my files?

Uploaded and compressed files are deleted automatically within two hours, usually after about one. Download your result before then.