Each page is redrawn as a compressed image, which dramatically shrinks scanned documents and photo-heavy PDFs. The trade-off: text in the compressed file can no longer be selected or searched, so keep the original if you need that.
Which level should I choose?
Balanced suits email and uploads. Smallest file is for strict size limits. Best quality keeps small text crisp.
Questions
Why is my PDF not getting smaller?
Text-only PDFs are already compact; turning them into images can make them bigger. If that happens you’ll be told and can keep the original.
Are my files uploaded?
No – compression happens in your browser.