Add Page Numbers

In a word processor, page numbers are a field: the software counts the pages and prints the answer, recalculating whenever the document changes. A PDF has no such mechanism. Numbering a PDF means drawing the character 7 at a particular point on the seventh page, and from then on it is ink like any other ink on the page.

The practical consequence is about ordering. If you add numbers and then insert, delete or reorder pages, the numbers do not follow — a page stamped 7 that moves to position 4 still reads 7. Numbering is therefore the last structural step, after the document's contents are settled.

It also means the numbers cannot be removed cleanly afterwards, since they are no longer distinguishable from the rest of the page content. Keeping the unnumbered original until you have checked the result is the cheap insurance.

Almost no real document wants the number 1 on its first sheet. A cover page carries no number. A contents page usually does not either, or carries a roman numeral. The number 1 belongs on the first page of actual content, which might be the third or fourth sheet.

That is why two separate settings exist and why the distinction is worth understanding. One controls which physical page the numbers begin appearing on, so the cover stays clean. The other controls what number that page displays, so it can read 1 even though it is the fourth sheet in the file.

The same pair handles the other common case: a chapter extracted from a larger work that must keep its original numbering, or a volume that continues from where the last one ended. Set the start number to 147 and the sequence runs from there.

Bottom centre is the safe default and the one most documents use, because it is furthest from where content usually sits. Bottom right suits documents that will be flicked through, since that is where a thumb lands. The alternating position, mirroring left and right on facing pages, is what you want for anything that will be printed double-sided and bound — it keeps every number on the outer edge, away from the spine.

Format carries meaning too. A bare numeral is right for most things. Page 7 of 20 tells a reader whether anything is missing, which matters for faxed or posted documents and for anything that might be photocopied in parts. Roman numerals are conventional for front matter, and a prefix is useful when a document is one part of a numbered set.

Whatever you choose, the margin distance is worth a moment. Numbers set too close to the trim edge can be clipped by printers that cannot print to the edge of the sheet, and numbers set too far in collide with the footer the document already had.

Because stamped numbers are frozen, the order of operations matters more here than with most tools. Merge, insert, delete and reorder first — every one of those changes which page is which. Number once the page list is final.

Bookmarks and numbering are independent and complement each other: numbers help a reader who is holding paper, bookmarks help one who is scrolling. Edit Bookmarks adds the second, and doing it after numbering means the bookmark labels can quote the printed numbers.

If you have already numbered a document and then had to change it, the cleanest route is to go back to the unnumbered version rather than trying to patch the sequence. Where that is genuinely impossible, Edit PDF can white out a stray number and type the right one over it.