Why a PDF May Not Get Smaller
Understand the difference between resaving PDF structure and shrinking scanned images.
Reviewed 2026-09-14 · ToolMarket
When optimization helps
Text and vector PDFs can sometimes lose structural overhead when resaved. Compare the displayed before-and-after sizes rather than assuming compression always works.
A PDF that is already optimized can even become slightly larger.
Image-heavy scans
If each page is essentially a large photo, resaving the PDF does not substantially shrink those photos. If you have the originals, resize the images first and build a new PDF.
Inspect small print, signatures, and stamps after reducing image size.