Changing the chapter font size does effect the toc font size - why? [duplicate]

i'm new to latex and i'm wondering why the toc font size does change when i change the chapter font size.

For example. what i do is:

\chapter{\Large{This is my chapter}}


and this part of code does effect the font size of this chapter in my toc. But why? How can i change the chapter font size but not the font size of this chapter in my toc?

(btw: sorry for my bad english)

Hope someone can help. Thanks guys!

marked as duplicate by Schweinebacke, CarLaTeX, Stefan Pinnow, TeXnician, Heiko OberdiekJul 17 '17 at 16:32

• Just out of curiosity: Why are you changing the font size of the chapter header in this way? – Mico Jul 17 '17 at 15:50
• Because the argument of \chapter is also used for the ToC entry or the running head. – Schweinebacke Jul 17 '17 at 15:53
• – Schweinebacke Jul 17 '17 at 15:57
• @Mico The related link doesn't fit to my problem because all i wanna do is just change the size of one specific chapter and not all of them. I want to change it because it has a large title and the style of it looks completly different compared to the other chapter titles. That's why i want to change the size of it. If i change the size to "Large" it fits perfect but the toc style will change also. – mtzE Jul 18 '17 at 11:26
• @mtzE - In that case, simply change \chapter{\Large{This is my chapter}} to \chapter[This is my chapter]{\Large This is my chapter}. By the way, do note that \Large is a "switch". It does not, repeat not take an argument. – Mico Jul 18 '17 at 11:33

I suggest that you use the titlesec package for this purpose. More instance, you can do something like:

\documentclass{book}
\usepackage{titlesec}
\titleformat{\chapter}[display]
{\Large\bfseries}{\LARGE\thechapter}{1ex}
{\vspace{2ex}}
\begin{document}
\tableofcontents
\chapter{Introduction}
\end{document}

• Could you please elaborate on this? It is usually helpful to include some code that solves the OP's issue. – TeXnician Jul 17 '17 at 15:53
• @TeXnician Done. – José Carlos Santos Jul 17 '17 at 16:04

The reason for this behaviour is that proceeding this way, Large is written to the .toc file, that \tableofcontents reads.

If you're using a standard class that with titlesec and just write in your preamble:

\usepackage{title}
\titleformat*{\chapter}{\Large}

• how do i change the font size of only one specific chapter title? I don't want to change all of them – mtzE Jul 18 '17 at 11:28
• You can use \titleformat* in the document body. To make it local, enclose the command and the chapter within a \begingroup\endgroup. – Bernard Jul 18 '17 at 11:40
• Thanks Bernard! But @Mico solved my problem in a comment above :) – mtzE Jul 18 '17 at 11:41