Page numbers matter more than they look. Without them, "the third paragraph on the page about indemnities" is the only way to point at something, which is fine in a five-page memo and unworkable in an eighty-page report. For court filings, academic submissions, and tender responses they are frequently a hard requirement rather than a nicety.
If your finished PDF has none, you have three routes, and the right one depends on how many pages you are dealing with.
Route 1: add them in the source, if you still have it
Always check this first. Word, Google Docs, InDesign, LaTeX and every other authoring tool insert page numbers as a field that updates itself, positions consistently, and survives later edits. Re-exporting takes a minute.
In Word: Insert → Page Number, then pick a position. In Google Docs: Insert → Page numbers. In LaTeX, it is on by default and fancyhdr customises it.
This gives you a proper document rather than numbers painted onto pages, and it is the only approach where inserting a page later does not break everything.
Route 2: automatic numbering on an existing PDF
For a document of any length, you want a tool that numbers every page in one pass.
Free command line. cpdf handles it directly, and with LaTeX installed pdfjam and pdftk can stamp a numbered overlay. For repeat work this is the fastest and most controllable option.
Free desktop. PDFsam Basic and PDF24 Creator both offer page numbering on Windows. LibreOffice Draw can do it with some manual work.
Acrobat Pro. Tools → Edit PDF → Header & Footer → Add, with control over position, format, starting number, and page range. The most flexible option if you have it.
Online tools. iLovePDF, Sejda, and Smallpdf all number pages free, with position and format options and a live preview. Genuinely easy — the usual caveats apply about uploading the document and free-tier limits.
Bates numbering is a related but distinct thing: sequential identifiers stamped across a whole set of documents for legal discovery, where numbering must be unique across thousands of pages rather than restarting per file. Acrobat Pro and dedicated legal tools handle it; general-purpose page numbering does not.
Route 3: doing it by hand
For a short document — under about ten pages — placing numbers manually with a text tool is perfectly reasonable and gives you exact control over position and style.
In Docento.app: select the text tool, click where the number belongs, type it, and set the size. Move to the next page and repeat in the same position. Export when you are done.
Two honest caveats. There is no automatic numbering here, so this is per-page work that becomes tedious quickly — past ten pages, use one of the automatic tools above. And keeping numbers in exactly the same position across pages by eye is harder than it sounds; zoom in, place the first one carefully, and use the arrow keys rather than dragging.
Getting the details right
Position. Bottom-centre or bottom-right are the conventions. Bottom-right is better for documents that will be printed single-sided and flicked through, since the corner is what a thumb exposes. For double-sided printing, numbers should mirror — outer edge on both sides — which manual placement makes fiddly and automatic tools handle.
Stay inside the printable area. Numbers placed very close to the page edge get clipped by printers, which cannot print to the very edge. Keep at least a centimetre of margin.
Size and typeface. Two points smaller than body text, in the same family, in black or grey. A page number that draws attention has failed.
Format. Plain 7 is standard. Page 7 is more explicit and fine for business documents. 7 of 24 is genuinely useful for anything printed, because it tells a reader whether they are holding the whole thing — worth the extra effort on contracts and reports that get physically distributed.
Where to start. Cover pages conventionally carry no number, and front matter is often numbered separately in roman numerals. If your PDF numbers must match printed folios or a table of contents, work out the offset before you start rather than after.
Watch for collisions. Check that numbers do not land on top of existing footers, footnotes, or content. Skim every page after adding them.
Once they are added
Numbers added as annotations should be flattened into the page before you send the document, so they cannot be moved or deleted and every viewer renders them identically.
And if you insert or remove a page afterwards, manually placed numbers are wrong from that point on with nothing to warn you. This is the strongest argument for fixing the source document instead — a decision you will appreciate the second time someone asks for a change.
Related: how to combine PDF files, how to extract pages from a PDF, and how to print a PDF correctly.
