Compress PDF
Shrink a PDF that is too big to email or upload — usually by 40–70% with no visible difference. Nothing is stored, however large the file.
- Never stored
- No queue, no waiting
- No signup, no watermark
How it works
Add your PDF
Drop the PDF onto the page. Nothing is queued or stored, so even a 200 MB file starts instantly.
Pick how hard to squeeze
Recommended suits almost everything. Light protects print quality; Maximum gets the smallest possible file.
Compress and download
You are shown the before and after size, then download the smaller file.
What is re-encoded, and what is left alone
At Light, Recommended and Strong the document is edited rather than rebuilt. Every embedded image bigger than about a hundred pixels square is decoded, capped on its longest side, re-encoded and swapped back into the same slot; nothing else in the file is touched, so the outline, form fields, annotations, attachments and document information all come through unchanged. A replacement is only accepted when it is at least five per cent smaller than what it replaces, which is why running the tool a second time on the same file mostly does nothing.
Every replacement image is written as 8-bit DeviceRGB. On a screen that is invisible. For print it is not, because an image stored as CMYK comes back as RGB and the separation then depends on whoever prints it. Images in indexed or ICC-based colour spaces are skipped for the same reason — reading them correctly needs the palette or the profile, and leaving them alone costs a little size and no risk.
Maximum is a different operation, not a stronger setting. What it hands back is a new document built from pictures of the pages, so everything that was not a picture ceases to exist: links, form fields, annotations, the bookmark outline, tag structure, attachments and the document information go with the text layer.
When you want something else
Ghostscript reaches parts of a file that re-encoding images cannot. gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -o out.pdf in.pdf rebuilds the whole document through its own interpreter: images are downsampled to a target resolution, fonts are re-subset to the glyphs actually used, and the page content is rewritten. That last part is what to reach for when a file is large and has hardly any images in it.
It also lets you say what should happen to colour — -dColorConversionStrategy=/LeaveColorUnchanged keeps a press-bound document in the colour space it was authored in — where a browser canvas only ever produces sRGB.
Frequently asked questions
How much smaller will my PDF get?
It depends entirely on what is inside. Scans and photo-heavy documents usually drop 50–80%. A PDF that is mostly text may barely change, because text is already tiny — and in that case the tool tells you so and gives your original back rather than pretending.
Will the quality get worse?
At Recommended, not in any way you will see on a screen: images are re-encoded and resized to a sensible ceiling while text and vector artwork are untouched and stay perfectly sharp. Light is gentler still for print work. Strong and Maximum trade visible image quality for size, and say so.
Is my PDF stored when it is compressed?
No. Nothing is stored. This matters here more than usual — the files people need to shrink are typically contracts, passports and bank statements being sent somewhere with an attachment limit.
Why does Maximum say the text stops being selectable?
Because it renders each page to a single image. That is what makes the file so much smaller, but the words become part of a picture, so they can no longer be selected, searched or copied. Use it only when size is the only thing that matters.
Can I compress a file that is already compressed?
You can try, and the tool will tell you honestly if there is nothing left to gain. Running compression repeatedly on the same file degrades images without helping the size.
Is there a file size limit?
No fixed limit — the practical ceiling is your device's memory. Large documents take longer because your own computer is doing the work, not a server queue.
Good to know: Text and vector artwork are already stored efficiently, so a text-only PDF has little to give — expect a few percent, not half. JPEG 2000 images are left untouched because browsers cannot decode them. Soft masks are deliberately skipped: re-encoding a transparency mask puts halos around everything it masks.
Put this tool on your website
Free for any blog, class page or help article. Paste one snippet and your visitors can use it right on your page.