# How do I change the default font size?

How can I change the default font size throughout the LaTeX document? Is this even possible?

• There are two general answers below if you need a more detailed answer improve your question please, and tell us at least which class you are using …
– Tobi
Feb 7, 2012 at 18:05

at least some document classes provide an optional argument to do this. for example,

\documentclass[12pt]{book}


will provide a changed set of font sizes (\footnotesize will be smaller, for example) in a coherent style.

• The memoir document class provides an extended range of font sizes (9 to 13 points). Feb 7, 2012 at 21:18

The standard classes have options 10pt, 11pt and 12pt to load configurations for a main font in the given size and matching sizes for headlines etc.

If your using KOMA-Script use the option fontsize=<size> to set a size that may differ from the above three.

To change the size of the main font only try \fontsize{<size>}{<skip>}\selectfont but this is not a real user command so one should know what he does when using it ;-)

• It's worth noting that the extsizes classes (extarticle, extreport, etc.) support font sizes from 8pt to 20pt. Apr 7, 2014 at 9:39

You can change the main font size and the other font sizing commands (as long as the font is scalable) through the fontsize package.

### The fontsize package option

The most basic way is to use the fontsize option which automatically sets the line spacing:

\usepackage[fontsize=10.8pt]{fontsize}


### The \changefontsize command

If you need precise line spacing you can use the \changefontsize command:

\usepackage{fontsize}
\changefontsize[12.8pt]{11pt}


Here is a minimal working example. The normal size and the normal line spacing are set to 11pt and 12.75pt respectively:

\documentclass{book}
\usepackage[T1]{fontenc}
\usepackage{blindtext}
\usepackage{cochineal}
\usepackage{fontsize}
\changefontsize[12.75]{11}
\begin{document}
\blinddocument
\end{document}


which gives:

### Printing samples

The values ​​of the font sizing commands can be obtained with the \printsamples command:

\printsamples


prints the values of the font size and line spacing for all the sizes defined by the package.

\printsamples{12.8pt}{11.2pt}[normalsize,tiny,tinyr,tinyrr,tinyrrr]


prints the values of the font size and line spacing for all the sizes declared in the optional argument.

Here is a minimal working example with the Cochineal font:

\documentclass{book}
\usepackage[T1]{fontenc}
\usepackage{cochineal}
\usepackage{fontsize}
\begin{document}
\printsamples{12.8pt}{11.2pt}[normalsize,tiny,tinyr,tinyrr,tinyrrr]
\end{document}


which gives: