Reference

What Bates numbering is, and why documents carry it

A plain description of a hundred-and-fifty-year-old convention: where the name comes from, how the counter behaves, and what stamping a number on a page does not accomplish.

Last updated September 18, 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?

It exists so that a page can be referred to. 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.