Compress PDF
Make a PDF smaller. Best for scanned or image-heavy documents. Everything runs in your browser — your file never leaves your device.
How to compress a PDF
- Choose a PDF file.
- Pick a compression level (start with Recommended).
- Press Compress PDF — the smaller file downloads automatically.
How does it work?
robinpdf re-renders each page as an optimized image and rebuilds the PDF, which dramatically shrinks scanned documents and image-heavy files. Because pages become images, selectable text becomes part of the picture — for purely text PDFs that are already small, compression may not help.
Beat email attachment and portal upload limits
<p>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.</p><p>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.</p>
What actually gets smaller, and what it costs
<p>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.</p><p>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.</p><p style="margin-top:2rem;"><a href="/compress-pdf" class="btn">Compress your PDF now →</a></p>
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.
Frequently asked questions
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.