What happens to internal PDF page numbers after removing pages from a PDF?
Removing pages from a PDF affects two distinct types of page numbering. The PDF internal page index (the logical page order used by the PDF viewer) is renumbered sequentially from 1 automatically when pages are removed — page 3 of the remaining document is always position 3 in the file's page tree, regardless of which pages were originally removed. However, visible page numbers printed within the page content (such as footer text like '12' or 'Page 12 of 50' that was part of the original document design) are part of the page's visual content and are not modified by page removal. The result is a gap: if you remove pages 1–11 from a 50-page document, the output PDF starts at internal page 1 but the first visible page footer still reads '12'. This matters in legal documents, reports with a table-of-contents, and books where the footer page numbers must match the PDF viewer's page count.