Why a PDF barely shrinks after compression
By PDFEditor.ae · Published
The short answer
Our Compress PDF tool is lossless: it reorganises how the PDF is stored but leaves every image exactly as it was. When most of a file is photos or scans, there is little else to optimise, so the size barely moves.
What we measured
We ran four test files through the tool on 10 October 2026. A 24-page text report printed from a browser shrank from 265,818 bytes to 107,784 bytes (59% smaller). A four-page PDF of photos went from 4,630,655 bytes to 4,629,093 bytes — effectively no change. Two files that had already been saved by our own merge and JPG to PDF tools did not shrink either, because they were already stored compactly.
Files that usually shrink very little
- Scanned documents, where every page is a photo of paper.
- PDFs made from phone photos.
- Files already optimised by another tool or saved by this site.
- Small PDFs, where there is little structure to remove.
What to do instead
If the images are the problem, make them smaller at the source: resize the photos, then rebuild the PDF with JPG to PDF. If the file is long, check whether the recipient accepts several files and split it.
- Resize or crop the original photos.
- Convert them again with JPG to PDF.
- Or split the PDF into parts with Split PDF or Extract Pages.