How PDF compression works here
Each page is re-rendered as an optimised image at a lower resolution and rebuilt into a new PDF. This works best for scanned documents and PDFs full of photos — certificates, ID cards, bank statements from a scanner — which often shrink by 50–90%.
Things to know
- Text in the compressed PDF becomes part of the page image, so it can't be selected or searched. Keep your original file.
- PDFs that are mostly digital text are already small and may not get smaller — the tool will tell you if that happens.
- Password-protected PDFs can't be compressed.
Need the PDF under a specific size?
Start with Recommended. If it's still too big, try Extreme. For photos of documents, you can also shrink the images with the image compressor and build a fresh PDF with Images to PDF.