Compress a PDF (reduce the file size)

How it works

Tap or click the box and choose your PDF; you can select several files at once and each is compressed on its own. The result line tells you exactly what you gained: the size before and after, and by what percentage the file shrank. The biggest savings come from phone scans and photo-heavy documents, which is often enough to bring a file under the upload limit of the portal or email service you are using. The savings come from re-encoding the photos and scans embedded in the pages; text, signature fields and the page layout are left untouched. If your document is mostly plain text with no images, there is little to squeeze — in that case the tool never inflates the file, it simply returns the original and says so. Keep your original file after downloading: image quality given up during compression cannot be restored.

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What is PDF compression?

PDF compression means reducing a document's file size without touching its layout or text. What actually takes up space in most PDFs is not the text but the photos and scanned pages embedded in them, so compression works by re-encoding those images more efficiently and compacting the document's internal structure. That is why the same setting can behave very differently on two files: a scanned form may drop to a tenth of its size while a plain text report barely changes at all.

What is Lossless compression?

Lossless compression rewrites data in a shorter form without discarding any information; when the file is opened, the exact original content comes back. In this tool that is what happens to the document structure: unused objects, leftover revision data and sparsely written tables are packed together. Re-encoding the images, on the other hand, is lossy — detail the eye barely notices is dropped for good to save space. Both layers work together, and the result line reports how many images were re-encoded.

What is the difference between lossy and lossless compression?

Lossless compression throws nothing away — it only writes the same information more efficiently, so repeating it never changes the content. Lossy compression permanently discards detail the eye can barely see: the file shrinks noticeably, but what was dropped never comes back. In this tool the document structure is compacted losslessly while images are re-encoded lossily. That is also why compressing an already-compressed PDF gains very little and costs a bit more image quality each round — always keep the original file.

What shrinks, and what stays exactly as it was?

Most of the gain comes from images embedded as JPEG: pages scanned with a phone or scanner and photos placed in the document fall into this class. The "Balanced" and "Strong" settings also cap the resolution of those images; the caps are chosen so a scanned A4 or Letter page stays readable on screen and in print.

Text, fonts, links and the page layout never change on any setting; selectable text stays selectable. PNG-like embedded graphics — diagrams, screenshots — are deliberately left alone: re-encoding them like photographs would blur their sharp edges for little gain. And if a re-encoded image comes out larger than the original, the change is rolled back; no image is ever enlarged in the name of compression.

Which strength should you pick?

"Balanced" is the right starting point for most jobs: email attachments, documents uploaded to application portals and scans you want to archive all shrink well and stay readable. If the result is still over your limit, try "Strong" — the drop in image quality is visible, but text remains legible.

"Light" is for documents where image quality comes first: a photography portfolio or a file headed to print keeps its full resolution, and only the encoding and the document structure are tightened. Whichever you choose, the result line shows the before and after sizes side by side; if you are not happy, run the original again with a different setting.

Frequently asked questions

Why did my file barely shrink?

Most likely your document has no images, or its images are already tightly encoded. What takes up space in a PDF is embedded photos and scans; a plain-text document has little left to squeeze. Re-compressing an already-compressed PDF also gains very little. The tool never makes things worse: if it cannot shrink the file, it returns the original untouched and says so in the result line.

Does compression damage the text or a signature?

Selectable text is never touched on any setting; fonts and layout stay as they are. On scanned pages, however, the text is part of the image itself: the "Strong" setting visibly lowers scan quality, though the limits are chosen to keep it readable. A scanned wet signature follows the same rule. For an official document where quality matters, stay on "Balanced" and keep your original file.

Can I compress a password-protected PDF?

No. An encrypted PDF stores its content scrambled, so the images inside cannot be reached; the tool tells you this with a clear message. Remove the password first with a program you trust, compress the file, and re-apply the password afterwards if you need it.

Is my file uploaded anywhere?

No. The PDFs you choose never leave your device; reading, re-encoding the images and saving all happen inside your browser. Once this page has loaded, compression keeps working even if your internet connection drops.