I deleted half the pages but the file size hardly dropped. Why?
Because size follows what the pages contain, not how many there are. A text page is very light, while photos and embedded fonts are heavy and stay in the file as long as any remaining page uses them. Removing image pages shrinks a file a lot, removing text pages barely changes it, and the tool does not compress what is left.
Where a PDF's size comes from
Picture a 20-page quotation: a cover with a large photo of your product, then 19 pages of tables and text. Text in a PDF is stored as characters and short drawing instructions, so a full page of table may take up only a small part of the file. The cover photo is stored with all its pixels, and on its own it can outweigh every table combined. Delete 10 pages of tables and you have removed a small slice of the weight, while the cover photo stays exactly as it was.
Why shared fonts and images stay
Many files embed a font once and every page uses it. The Delete PDF pages tool copies into the new file everything the remaining pages need to display correctly. So as long as one page is written in that font, the whole font comes along. The same goes for a logo repeated in every page header: it is one shared image, and deleting half the pages does not delete half of it.
Some programs also export files where all pages point at one shared list of resources, so every page 'refers to' every image. In a file like that, a deleted page's images can travel with a remaining page, and the size does not drop as you expect. That comes from how the original was built, not from the deletion.
When the size really does drop
- When you delete pages with their own images, such as product photo pages or scanned pages. In a scanned file every page is a separate image, so removing half the pages comes close to halving the size.
- When you delete pages that use a font no other page uses, such as an appendix in another language.
- When the original holds earlier saved versions inside it. The new file is built from scratch, so those versions do not come across.
A 20-page file: a cover with a large photo and 19 text pages, and you delete pages 11-20.
Summary: Pages to delete: 11-20 (10 of 20). Pages that will remain: 10.
The page count halves, but the size drops only a little, because the heavy cover and the shared font are still there.
If what you need is a smaller file
Deleting is for removing pages, not for compression. The tool copies the remaining pages as they are without recompressing images, which is what keeps their quality. If the file is over an email or upload form limit, find the heaviest page and ask whether you need it. Often it is the cover or a page with a phone photo. If every page is essential, the fix is to shrink the images at the source and export the file again.
Common questions
Can the new file come out bigger than the original?
It can differ slightly either way, because the file is written fresh with a different internal layout. When you remove pages with heavy content, though, the difference is clearly downward.
How do I see the new file's size?
After the download starts, the tool shows a message with the number of pages removed and remaining and the size of the new file.