PDF compression levels explained

Not all “compression” is the same. Some methods change nothing you can see; others trade sharpness for size. Knowing which is which lets you shrink a file without regrets.

High quality (lossless)

This rewrites the PDF’s internal structure and drops unused data — object streams, duplicate resources, leftover bookkeeping. Nothing about how the page looks changes, and text stays selectable. It’s the safe default, and best for text-heavy documents. Image-heavy files may not shrink much this way.

Balanced and Maximum (rasterized)

These render each page to a JPEG and rebuild the PDF from those images. That’s dramatically smaller for scans and photo-heavy pages — but the text becomes part of an image, so it’s no longer selectable, and very small text can soften. Maximum pushes size down further than Balanced.

• Text document you’ll keep editing or searching → High quality.
• Scan or photo-heavy PDF for sharing → Balanced.
• Smallest possible for archiving, sharpness less critical → Maximum.

The tool reports the before and after size. If a mode doesn’t actually make the file smaller, it says so — keep your original in that case.

A shortcut for print

If a document is only going to be printed in black and white, converting it to Grayscale first drops the colour channels and often shrinks the rasterized result further, while saving colour ink.