Bates numbering: what it is and why documents carry it

Bates numbering stamps every page of a document production with a unique, sequential identifier such as CHEN-000142, so that any single page can be cited exactly. The counter runs continuously across the whole production; this page covers where the name comes from, how the counter behaves, and what stamping a number does not accomplish.

By Martin Ferret · Published September 18, 2026 · Last updated October 27, 2026

What is Bates numbering?

A Bates number is a unique, sequential identifier stamped on every page of a document set. It usually sits in the bottom right corner, and it usually looks like a short prefix followed by a zero-padded counter.

CHEN-000142

The name comes from the Bates Automatic Numbering Machine, a self-incrementing hand stamp patented in the nineteenth century. The machine is long gone; the convention it created outlived it by a century and a half.

What is Bates numbering for?

Bates numbering exists so that any single page of a production can be cited exactly. Someone says “CHEN-000142” and everyone in the room turns to the same piece of paper, whatever order their copies are in and whatever the document was called when it was produced.

Without it, a four-hundred-page production is materially impossible to discuss. Page numbers do not survive being split, merged or reordered; a Bates number is attached to the page itself.

The convention is not specific to any area of practice. It is the same in a commercial dispute, an employment claim and a family-law matter: a divorce or custody production numbers its pages the way every other production does, and a chat export joins that sequence rather than starting its own.

How does the numbering behave?

Conventions of Bates numbering
Continuous across a production	The counter does not restart with each document. If five hundred pages have already been produced, the next document starts at 000501.
A stable prefix	Usually initials of a party, a matter, or the producing firm. It is what distinguishes one production from another.
Zero padding	A fixed counter width, commonly six digits, so the numbers sort correctly as text and the stamp keeps the same footprint on every page.
One number per page	Not per document and not per exhibit. A hundred-page exhibit consumes a hundred numbers.

A confidentiality designation often shares the same footer, on the opposite side from the number.

CONFIDENTIAL              PAGE 142 OF 147              CHEN-000142

That footer, on a real page, is on the sample exhibit, alongside the certificate page the numbering deliberately skips.

What is a Bates index?

A production is usually accompanied by an index that maps ranges back to what they contain, so a reader can find the right pages without opening the whole set.

The first and last Bates number of each document.
What the document is.
The date range it covers.

Kept as a spreadsheet, it is also what lets the next production start at the right number instead of colliding with the last one.

What does Bates numbering not do?

What it does do is make a document usable: citable in a filing, referable in a deposition, and findable a year later. That is the whole of it, and it is enough to matter.

ChatExhibits stamps Bates numbers because documents that will be produced need them. It does not decide, and cannot decide, what any court will accept. Whether the file itself has been altered is a different question, answered by a SHA-256 digest.

For where Bates numbers sit among everything else a custody production of chat messages involves, see How to use WhatsApp messages as evidence in a custody case.

Common questions

How is a Bates number different from a page number?

A page number restarts with every document. A Bates number continues across the whole production, so no two pages anywhere in it share one, and a page keeps its number when documents are split, merged or reordered.

Does the cover or certificate page get a Bates number?

In a ChatExhibits exhibit, no. The certificate page, and the declaration page when there is one, are left unnumbered, and the count starts on the first page of the conversation.

Can numbering continue from an earlier production?

Yes. ChatExhibits asks for the prefix and the starting number before it generates anything, and remembers in your browser where the last production ended, so the next one can pick up from there.

What happens when the counter runs out of digits?

ChatExhibits refuses and says so, rather than widening the number. A seven-digit number in the middle of a six-digit production would break the sequence that makes the pages citable.

How do you cite one message rather than a whole page?

A page can hold many messages, so a ChatExhibits exhibit also gives every message a paragraph number in the margin. The Bates number cites the page; a reference such as ¶ 412 cites the message.