# Font size different in \newtheorem heading and body text versus the rest of the document

I am using the book document class with no font size specified, so it should be the default 10pt.

After \begin{document} I have the line \fontsize{9}{10.8} to change all the font to 9pt.

\documentclass{book}

\usepackage{bookman}
\usepackage{amsthm}

\newtheoremstyle{break}
%{\topsep}{\topsep}%
{8pt}
{8pt}
{}{}%
{\bfseries}{}%
{\newline}{}%
\theoremstyle{break}
\newtheorem{test}{Test}
\counterwithin*{test}{subsection}

\begin{document}

\fontsize{9}{10.8}

The quick brown fox jumps over the lazy dog. This font looks to be 9pt.

\begin{test}
This is the test.  This seems to come out smaller.
\end{test}

\end{document}


The heading "Test" and the body text are smaller than the 9pt specified in \fontsize.

What smaller font size is this? And can I get the entire document to output in this smaller font size with \fontsize? Or is \fontsize causing these two sizes of fonts?

• It is impossible to debug disconnected fragments, Please edit the question so that it has a small but complete document that shows the issue. Remove any packages that are not needed to show the problem. – David Carlisle Feb 14 at 8:54
• You are missing \selectfont after the \fontsize declaration. The "smaller" size is in fact the requested 9pt. But this is not the best way to set a smaller font size for the whole document, as any macro calling \normalsize will revert to 10pt. – campa Feb 14 at 9:41

The declaration \fontsize{9}{10.8} doesn't take effect until \selectfont is issued. This happens in the theorem, but not in the text above it.

\documentclass{book}

\usepackage{bookman}
\usepackage{amsthm}

\newtheoremstyle{break}
%{\topsep}{\topsep}%
{8pt}
{8pt}
{}{}%
{\bfseries}{}%
{\newline}{}%
\theoremstyle{break}
\newtheorem{test}{Test}
\counterwithin*{test}{subsection}

\begin{document}

\fontsize{9}{10.8}\selectfont

The quick brown fox jumps over the lazy dog. This font looks to be 9pt.

\begin{test}
This is the test.  This seems to come out smaller.
\end{test}

\end{document}


On the other hand, using a specialized class for this seems better.

\documentclass[9pt]{extbook}

\usepackage{bookman}
\usepackage{amsthm}

\newtheoremstyle{break}
%{\topsep}{\topsep}%
{8pt}
{8pt}
{}{}%
{\bfseries}{}%
{\newline}{}%
\theoremstyle{break}
\newtheorem{test}{Test}
\counterwithin*{test}{subsection}

\begin{document}

The quick brown fox jumps over the lazy dog. This font looks to be 9pt.

\begin{test}
This is the test.  This seems to come out smaller.
\end{test}

\end{document}

• Thanks. Perfect. – E2R0NS Feb 14 at 9:46