Compress PDF

Why PDF file size gets out of hand

Most oversized PDFs have one culprit: images. A document scanned at high resolution, a report full of screenshots, or a brochure exported from design software can easily reach 20–50MB even when the text content is tiny. Email providers typically cap attachments at 25MB, government and job portals often enforce limits as low as 1–2MB, and messaging apps compress or reject large files. That gap between what tools produce and what platforms accept is why PDF compression is one of the most-used document operations in the world.

Compression works by re-encoding the images inside your PDF at a smarter quality-to-size ratio, downsampling resolution that no screen or printer will ever show, and stripping redundant metadata. Text and fonts are left untouched — which is why a well-compressed PDF looks nearly identical to the original at a fraction of the size.

How to get the smallest file without visible quality loss

PurePDF gives you three presets plus a custom target. For most documents, Balanced is the right choice: it typically cuts 50–70% of the file size with no visible difference on screen. Use High Quality when the PDF will be printed professionally, and Extreme when you must hit a hard limit like "under 1MB" for a government portal.

• Compressing to a specific size? Use the custom target slider instead of guessing with quality levels — the engine iterates until it hits your number.
• Scanned documents compress the most (often 80–90%), because scanner output is heavily over-resolved.
• If a text-only PDF barely shrinks, it was already efficient — there is simply little left to remove.
• Compress before merging, not after: smaller inputs make every downstream step faster.

Why compress with PurePDF instead of other tools

Unlike almost every competing service, PurePDF compression runs entirely in your browser using a WebAssembly build of Ghostscript — the same engine used in professional print workflows. Your file is never uploaded to a server, which means there is nothing to intercept, store, or leak. That makes it safe for contracts, financial statements, and medical documents that should never leave your machine.

There are also no daily limits and no watermarks. Smallpdf caps free users at roughly two tasks per day; iLovePDF limits file sizes. PurePDF compresses two PDFs at a time without an account, five at a time with a free one, as many times a day as you like.

Troubleshooting common compression problems

If your compressed PDF looks blurry, you likely used Extreme on a document that will be read at high zoom — recompress the original with Balanced instead. If the file barely shrank, check whether it is mostly text (already efficient) or was previously compressed. And if the PDF is password-protected, unlock it first — encrypted files cannot be recompressed until the encryption is removed.