How to add page numbers to a PDF
- Drop your PDF into the zone above, or click to browse and select it.
- Choose a position — bottom center is standard for most documents; bottom right suits formal reports.
- Set the starting number. Use 1 for a standalone document, or a higher number if this PDF continues a larger work.
- Click Add numbers & download. The numbered PDF saves directly to your device.
Everything runs in your browser using pdf-lib.
No file is uploaded — open DevTools (F12) → Network while processing to confirm zero outbound requests.
When to add page numbers to a PDF
- Preparing a document for printing — readers can navigate and reassemble printed pages easily with numbered footers.
- Formal reports and submissions — legal filings, academic submissions, and business proposals are expected to have page numbers.
- Multi-chapter documents — number each chapter PDF starting from where the previous one ended to create consistent pagination across a series.
- Scanned documents — add numbers to a scanned PDF that was produced without them.
- Contract annexures — stamp page numbers before sending contracts for signature to prevent page substitution.
How it works under the hood
pdf-lib loads your PDF and provides access to each page's content stream. For every page, the tool
calculates the position of the page number text based on the page's actual dimensions (which may vary
if the PDF has mixed page sizes), then calls page.drawText() to add a Helvetica text
element at the correct coordinates.
Helvetica is one of the 14 standard PDF fonts — it is available in every PDF viewer without needing to be embedded in the file, which keeps the output file size nearly identical to the input. The text is drawn as a proper PDF text object, so it is selectable and searchable in the output document.
Limits and what to expect
- Font and size: Helvetica at 11pt. These are fixed to keep the tool simple and the output consistent — custom fonts and sizes are not currently available.
- Margin overlap: numbers are placed at a fixed margin from the page edge. If your PDF has content running to the very edge (no margin), numbers may overlap the content — check the output before sharing.
- Mixed page sizes: the tool handles PDFs with different page dimensions correctly, placing numbers at the same relative position on each page regardless of size.
- Existing page numbers: if the PDF already has printed page numbers, this tool adds a second set on top of them. Remove the old numbers first using a PDF editor.
- Password-protected PDFs: must be unlocked before use. The tool will fail on PDFs that restrict content editing.
Page number position: which to choose
Position is mostly a convention question rather than a technical one, but it matters for readability and the type of document you are producing.
- Bottom center: The default for most documents. Readers expect it, and it does not compete visually with the document's header or sidebar content. Works for reports, proposals, academic papers, and general business documents.
- Bottom right: Standard for legal filings and court documents in many jurisdictions. When a reader holds a document in their right hand, the bottom-right corner is the first place they look to orient a page. Most legal formatting guides specify bottom right.
- Bottom left: Less common. Sometimes used in multi-column layouts where the right side of the page carries other content. Avoid for documents readers will print and bind on the left edge — the page number lands near the binding and may be obscured.
- Top center / top right: Used in long technical documents, manuals, and textbooks where the reader is expected to flip pages quickly. Top placement allows orientation at a glance without flipping to the foot of the page. Less standard for short business documents.
For most business use — reports, proposals, contracts — bottom center or bottom right is the right choice. When in doubt, check if there is a style guide for the document type you are producing; legal jurisdictions, academic institutions, and government agencies often specify page number placement explicitly.
Starting page number: when to use something other than 1
The starting page number option is useful in a few specific scenarios that come up often in practice:
- Continuing a series of documents: If you are producing a report in sections and each section is a separate PDF, number them continuously. If Section 1 is 24 pages, Section 2 should start at page 25. The reader and any table of contents that references page numbers will align correctly.
- Front matter conventions: Long documents often use Roman numerals (i, ii, iii) for front matter — table of contents, foreword, executive summary — and Arabic numerals starting at 1 for the body. This tool adds Arabic numerals; apply it separately to the body PDF and handle front matter numbering in your source document before converting to PDF.
- Inserting pages later: If you add a new section at the front of an already-numbered document, you may need to re-number the existing pages starting from the offset. Set the starting number to match where the document content begins in the final pagination.
How PDF font embedding affects page number file size
One subtle advantage of using the 14 standard PDF fonts (like Helvetica, which this tool uses) is that they are not embedded in the file — every PDF viewer has them built in. This means adding page numbers to a PDF with this tool increases the file size by essentially nothing. The page number text objects are small, and no additional font data is added to the file.
By contrast, tools that use custom fonts for page numbers must embed the entire font file — which can add tens of kilobytes per font. For a document you intend to email or upload to a portal with file size limits, Helvetica page numbers are the efficient choice.
Privacy compared to other page numbering tools
Most online PDF tools upload your document to their server to process it. For reports containing financial projections, legal filings, or client data, that upload is a potential data leak — regardless of what the tool's privacy policy says about deletion windows.
keptlocal stamps page numbers entirely inside your browser. Your PDF bytes never leave your device. Open the Network tab in DevTools and run the tool — you will see no upload requests at all.