Page numbers are usually demanded rather than wanted. Courts require them on filed bundles, universities require them on submissions, and anyone assembling a document from several sources needs them because the parts arrived unnumbered.
What gets added
A plain number, centred at the foot of each page, in grey Helvetica at 10 point, about a third of an inch from the bottom edge. It is drawn as real text rather than as an image, so it stays crisp at any zoom, prints at full resolution and can be selected and searched like any other text in the document.
Numbering starts at 1 on the first page of the file and counts every page including blanks and covers. That is what "page numbers" means for a legal bundle or a submission — the position in the document, not a logical numbering that skips the front matter.
Watch the bottom margin
The number is drawn on top of the existing content, not inserted into a reserved space. Pages are not resized or shifted to make room, because that would mean re-laying-out the document, which is not something that can be done reliably to an arbitrary PDF.
So if your pages already have something at the very bottom — an existing footer, a page number the original document supplied, a table running to the edge, or a scan with no margin — the new number will overlap it. Check the first and last pages before relying on the result. Documents with a normal margin have plenty of room.
Everything else is untouched
- Existing page content is copied rather than re-rendered, so text stays selectable and images keep their original bytes.
- The file grows by a few kilobytes — one embedded font and a short text instruction per page.
- Pages already carrying their own numbering keep it; you will have two sets, which is sometimes exactly what a court bundle requires and sometimes a mess.
- The added numbers can be removed later only by a PDF editor, since they become part of the page content.
Order first, number second
If you are also merging, reordering or deleting pages, do all of that before numbering. Numbers are stamped based on position at the time they are applied, so rearranging afterwards leaves you with a document whose printed numbers no longer match its order — which is worse than having no numbers at all.
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