How to compress a PDF without wrecking quality

A PDF is usually large for one of two reasons: it carries redundant structure, or it is full of high-resolution images. The right fix depends on which one you have — and picking the wrong one either wastes effort or blurs your text.

Start with lossless

The High quality mode rewrites the file with object streams and drops unused data. Nothing about how the page looks changes — text stays selectable and crisp. On a text-heavy PDF assembled from several sources this alone can shave off a meaningful chunk.

If a mode doesn’t actually make the file smaller, the tool tells you so — keep your original in that case.

When to rasterize

Scans and image-heavy PDFs barely shrink losslessly because the weight is in the images. The Balanced and Maximum modes render each page to a JPEG and rebuild the document, which shrinks those files dramatically.

• Balanced: good for most scans; text becomes an image but stays readable.
• Maximum: smallest result, best for archiving where sharpness matters less.
• Trade-off: selectable text becomes a picture, so run text extraction first if you need the words.

Grayscale as a shortcut

If a document is only going to be printed in black and white, converting it to grayscale first drops the colour channels and often makes the rasterized result noticeably smaller — while also saving colour ink at the printer.

Hitting a specific size

If you have a hard limit (an email or upload cap), aim for it directly rather than guessing a quality number: rasterize, check the reported before/after, and step up the mode if you are still over.

Every mode runs entirely on your device — the PDF is never uploaded.