Compress PDF
Make a PDF smaller. Best for scanned or image-heavy documents. Everything runs in your browser — your file never leaves your device.
For portals and forms with an upload limit. The best quality that fits is used.
How to compress a PDF
- Choose one PDF, or several.
- Pick a compression level (start with Recommended).
- Press Compress PDF — the smaller file downloads automatically.
Why files need shrinking
Most compression happens because an email, a job portal or a public administration form rejects anything above a few megabytes. Those are exactly the documents with personal data: payslips, medical reports, scanned contracts. A cloud compressor needs a copy of each one.
How it shrinks the file, and what that costs
Only the photographs are recompressed: scaled down and re-encoded as JPEG, harder at each level. Text stays text you can select, search and copy, and fonts, drawings and links are copied untouched. Print files in CMYK are drawn the way a PDF viewer shows them before being re-encoded, so colours come out the same. The cost is photo sharpness: zoom in on a detailed page of a copy before sending the smallest version.
Limits
A PDF that is mostly text, or whose images are already small or JPEG 2000, will barely shrink, because there is little weight to take out; then nothing is downloaded and the page says so. Scans made in black and white (fax-style) are already tiny and are left as they are.
How does it work?
robinpdf recompresses the photographs inside the PDF and leaves everything else exactly as it was: text stays text you can select, search and copy, and fonts, drawings and links are untouched. Photos are scaled down and re-encoded more or less strongly depending on the level. That is where the weight of almost any heavy PDF is, so scans, brochures and photo reports shrink a lot, while a document that is mostly text barely changes because there is little to take out.
Beat email attachment and portal upload limits
The usual trigger for compressing a PDF is a hard limit somewhere else. Gmail caps attachments at 25 MB, Outlook at 20 MB, and many job boards, government portals and court filing systems stop you at 10 MB or even less. A phone-scanned contract can easily weigh 30 MB, so the upload fails even though the content is just a few pages of text.
Compression brings that scan down to a fraction of its size, usually with no visible difference on screen. It is worth compressing before sharing even when nothing blocks you: smaller files send faster, open faster on the recipient's phone and do not clog inboxes. If a file must land under a specific limit, compress it first and check the resulting size before you upload.
What actually gets smaller, and what it costs
Almost all the weight in a heavy PDF is images. Text and vector graphics are already tiny, which is why a 200 page text-only contract can weigh less than a single scanned page. Compression works by re-encoding and downsampling those images, so scans, photo reports and image-heavy brochures shrink dramatically, while a document that is pure text will barely change because there is nothing significant left to squeeze.
The trade-off is image sharpness. For documents that will be read on screen, a stronger setting is usually indistinguishable from the original and saves the most space. If the file will be printed, or someone needs to zoom into fine detail, stay conservative. Compress a copy, open it, and zoom to 200 percent on a detailed page before deciding.
Is it private?
Yes. Everything runs inside your web browser, using your own device. Nothing is uploaded to any server, so your documents stay completely private. How does this work without uploading?
Frequently asked questions
Can I compress several PDFs at once?
Yes. Choose or drop as many as you like and they are compressed one after another, right here in your browser, with the same setting for all of them; the result downloads as a single ZIP. Files that are already small are kept as they were, and a file that cannot be read does not stop the rest.
How much smaller will my PDF get?
It depends on what is inside. Scanned documents and image-heavy files often shrink by 50 to 90 percent, while text-based PDFs may only lose a few percent because text takes up almost no space to begin with. Compress a copy and compare the sizes to see what your particular file gains.
Does compressing a PDF make the text blurry?
Real text stays perfectly sharp, because it is stored as fonts and vectors rather than pixels, and only embedded images are downsampled. The exception is scanned pages, where the text is itself a photograph, so very aggressive compression can soften it. If a scan must stay crisp, use a milder setting.
Why did my file barely shrink?
It was probably already efficient. Text-only PDFs, files exported with optimization enabled, and documents that were compressed once before leave little room for further savings. Compressing a second time rarely helps and is not worth any additional quality loss.