How do I increase the default font size of all slides in Beamer?

I found in the question How to set a small default font size with beamer? that you can reduce the default font size in Beamer by writing

\documentclass[8pt]{beamer}


However, the answer to this question doesn't explain how I can make the default font size bigger rather than smaller.

My questions are:

1. What is the default font size?
2. What other default font sizes are supported besides 8pt?

Note: I was able to find the answer to this question on my own, but I am posting the question here because I believe that the answer would be useful to others.

• I take it you know that it is perfectly ok to answer your own question? So please add your answer. – Peter Jansson Jun 13 '16 at 10:33
• For an overview see beamer user guide "18.2.1 Choosing a Font Size for Normal Text" – user36296 Jun 13 '16 at 10:57

Edit: I am grateful to samcarter who pointed out that the information that I provided below is also available in the beamer user guide "18.2.1 Choosing a Font Size for Normal Text".

I was able to find that in the source code of the beamer.cls file, there are relevant lines:

\def\beamer@size{{size11.clo}}

\DeclareOptionBeamer{8pt}{\def\beamer@size{{size8.clo}}}
\DeclareOptionBeamer{9pt}{\def\beamer@size{{size9.clo}}}
\DeclareOptionBeamer{10pt}{\def\beamer@size{{size10.clo}}}
\DeclareOptionBeamer{11pt}{\def\beamer@size{{size11.clo}}}
\DeclareOptionBeamer{12pt}{\def\beamer@size{{size12.clo}}}
\DeclareOptionBeamer{14pt}{\def\beamer@size{{size14.clo}}}
\DeclareOptionBeamer{17pt}{\def\beamer@size{{size17.clo}}}
\DeclareOptionBeamer{20pt}{\def\beamer@size{{size20.clo}}}


These lines indicate that the default font size is 11pt, and that the options Xpt are available for X in {8, 9, 10, 11, 12, 14, 17, 20}. Furthermore smaller (same as 10pt) and bigger (same as 12pt) are available. All options besides 10pt, 11pt and 12pt require the extsize package to be installed.

MWE: 20pt

\documentclass[20pt]{beamer}

\begin{document}

\begin{frame}{}
This is 20pt.
\end{frame}

\end{document}


MWE: 8pt

\documentclass[8pt]{beamer}

\begin{document}

\begin{frame}{}
This is 8pt.
\end{frame}

\end{document}


• These options are listed in the manual as well, see the comment by samcarter to your question. – Torbjørn T. Jun 13 '16 at 11:53
• And notice that some options are only available depending on other packages to be installed. – user36296 Jun 13 '16 at 12:01
• I added smaller and bigger as options. Hope that's ok with you. – user36296 Jun 13 '16 at 12:22