How to change the chapter number to display as text (One, Two, …)?

Question

In LaTeX, how do I change the chapter number to display as text? eg:

CHAPTER ONE not CHAPTER 1;

CHAPTER THIRTEEN not CHAPTER 13.

Answer 1

Short answer: put the following code before \begin{document}.

\usepackage{fmtcount,etoolbox}
\makeatletter
\patchcmd{\@makechapterhead}{\thechapter}{\Numberstring{chapter}}{}{}
\patchcmd{\chaptermark}{\thechapter}{\NUMBERstring{chapter}}{}{}
\makeatother

Change \Numberstring into \numberstring if you don't want the number name capitalized.

A longer answer requires more information from you, that you can add to your question.

A quick solution would be also

\usepackage{fmtcount}
\renewcommand{\thechapter}{\Numberstring{chapter}}

but this will have some consequences on the typesetting of the Table of Contents (but also of headers). Choosing a strategy depends on the actual needs (and also on the class used).

Answer 2

The memoir documentclass provides this by default for some of the chapter styles. Consider reading the documentation; specifically section 6.5.1. Defining a chapter style (p 83).

Alternatively, also view some of the self-created code on Vincent Zoonekynd's LaTeX page for Chapters.

Answer 3

You can also try fncychap package.