How to Add Page Numbers to a PDF

The document is assembled, agreed and ready to go out, and the pages carry no numbers. In a contract or a court exhibit that is not cosmetic: without numbers nobody can cite a particular sheet, and an unbound set cannot be put back in the right order.

What lands on the page is a label, not a digit

The first thing worth knowing before you start: the tool stamps a line reading "Page 7", not a bare numeral. The word comes from the interface language you opened the site in, and there is no separate setting for it.

For an internal document, a bundle of exhibits or a filing set that is exactly right: the label reads unambiguously and never gets confused with numbers from the original layout. For typesetting work, where a single digit belongs on the folio, the behaviour comes as a surprise, and the interface offers no way around it.

Where the number actually lands

There are six positions, and their margins are fixed. They cannot be adjusted.

Bottom centre is the default. Font size is set separately, from 6 to 36 points, defaulting to 10, which suits A4 and Letter.

The last row of that table does not exist for numbering. A number in the middle of the page reads badly over the text and almost always gets in the way; the position is inherited from the shared vocabulary of stamp placements and has no real use here.

How to number the document

1. Open add-page-numbers and upload the file. 2. Mark the pages on the preview grid if you need to: only marked pages are numbered. 3. Choose the position and the font size. 4. Set the start number if the count does not begin at one. 5. Run the job and download the result. 6. Open the first and last numbered pages and check whether the label ran into the content.

The count runs inside the selection, not across the document

This is the tool's main piece of non-obviousness, and it is also the answer to its most common request.

Mark the pages from the third to the last and leave the start number at one, and the third physical sheet gets "Page 1", the fourth gets "Page 2" and so on. The counter is tied to the ordinal position within the selection, not to where the sheet sits in the file.

Tested on a four page document: selecting pages three and four with a start number of one produced "Page 1" on the third sheet and "Page 2" on the fourth. The first two carried no label at all.

Hence the recipe for documents with a cover and a contents page: do not hunt for the right start number, just leave the opening sheets out of the selection. The body of the document then starts at one by itself.

The reverse works too. If the third sheet has to read "Page 3", select it and set the start number to 3.

The selection does not have to be contiguous either. Mark scattered sheets and the count runs through them consecutively: the first marked sheet takes the start number, the second takes the next one, however many unnumbered pages lie between them.

What the start number can and cannot do

The start number accepts values from 1 to 100000. The upper bound is generous, and it exists for the case where a file is part of a larger matter and continues somebody else's numbering.

The lower bound is hard: there is no zero and no negative. Making the cover "page 0" is not possible, and that is a deliberate limit rather than an oversight.

Roman numerals, letter indices and a "7 of 24" format are equally unknown to the tool. The label follows one template: a word and an Arabic number. Numbering along the lines of "Exhibit 2, sheet 4" has to come from somewhere else.

The document is not rasterised, but it does gain weight

The number is laid onto the real page, not over a picture of it. The text layer, the links and the bookmarks stay where they were, so a numbered document searches and copies exactly as it did before.

The bulk of the price is paid once. The font the label is set in is embedded into the file, and on a short document it is almost the whole increase; the labels themselves weigh a few bytes.

Between the second row and the third lie ten more numbered sheets and under three kilobytes of difference. Most of the increase is a one-off, around thirteen kilobytes, and every stamped sheet then adds about three hundred bytes on top. On a three hundred page report that came to 105 KB: still one font, but at that length the per-page part outweighs it.

It does still fix an order: compress after numbering, not before. If a document needs both, put the numbers on and then run the result through compress-pdf.

The label sits on top, with nothing behind it

No white rectangle is drawn under the label and no transparency is applied. Dark grey text is simply placed on the page at the chosen point, and if something is already there, the two overlap.

The usual casualty is the source document's own footer. Numbering sits 12.7 mm from the bottom while a typical footer sits lower, so the two labels usually clear each other. In documents with tight layout, with footnotes, or with typeset numbers already in place, checking is not optional.

One more detail: if the line comes out wider than the page, the coordinate hits a clamp and the label is pinned to the very edge. Nothing breaks, but it looks exactly like text pressed against the edge of a sheet.

The order everything else goes in

Numbering is nearly always the last structural operation on a document, and the order here is not a matter of taste.

Assemble the document before numbering it. Stitch files together with merge-pdf after each has been numbered separately and the finished bundle restarts its count in every part. The same goes for organize-pdf: any reordering after numbering leaves the labels where they were, and the sequence of digits stops matching the sequence of pages.

Orientation the tool sorts out by itself. Before stamping, a page's rotation is transferred into its content, so the number lands at the visible bottom of the sheet even on pages turned by 90 degrees. Tested: the rotated page came out landscape, 842 by 595 points, with the label 34 points from its bottom edge, exactly as on the portrait pages around it.

The side effect lies elsewhere. A rotated page stops being rotated in the result: the rotation flag comes off and the sheet becomes genuinely landscape. It looks the same, but a system that reads that flag sees a different document. If orientations need evening out deliberately, that is rotate-pdf, and it belongs before the numbering.

A last word about neighbours on the page. If the document also needs a "Copy" or "Confidential" stamp, that is add-watermark, a separate operation with its own placements and opacity. Run it before numbering and pick different corners, or the two lines will meet at one point.