Why your PDF will not get smaller

A PDF is a container for text, fonts, pictures and other objects. Two documents with the same number of pages can have very different sizes. Text can be stored compactly, while a full-page photograph can consume much more space.

Start with content-preserving optimization

The Optimize mode in Compress PDF rewrites the file using compressed object streams. This can reduce overhead, but it does not downsample photographs. If a document has already been optimized, the gain may be small or zero.

Use image-based compression selectively

Image-based mode renders each page, then stores a compressed picture of that page. It can help with image-heavy documents. It can also make a small text PDF larger. Searchable text, links, forms and document accessibility structure are lost in this mode.

Know when to keep the original

PDFReadyGo compares file sizes and offers the original when the new file would be larger. That is an honest outcome, not an error. If a portal’s limit is still too low, consider extracting only the required pages or asking whether separate attachments are allowed.

Review readability

Zoom into small text, figures and signatures before submitting an image-based copy. A smaller attachment is only useful if the recipient can still read it.