# Decreasing the font size in one node in a TikZ diagram

I have a diagram in which the font size for a node containing the measure of an angle is too big. What is the default font size for a node? What is the font size, in units of pt, for the specification font=\footnotesize in a node command?

\documentclass{amsart}
\usepackage{amsmath}
\usepackage{amsfonts}

\usepackage{tikz}
\usetikzlibrary{calc,angles,positioning,intersections,quotes,decorations.markings,decorations.pathreplacing}

\begin{document}
\begin{tikzpicture}

%A triangle is to be drawn on the Cartesian plane.
\coordinate (E) at (0,0);
\coordinate (A) at (0,{(4/3)*sqrt(3)});
\coordinate (D) at (4/3,0);
\coordinate (B) at ($(A)!{(8/3)*1cm}!90:(D)$);
\coordinate (C) at ($(D)!{(8/3)*1cm}!-90:(A)$);

\node[anchor=-75, inner sep=0] at ($(A) +({-75+180}:0.15)$){$A$};
\node[anchor=-75, inner sep=0] at ($(B) +({-75+180}:0.15)$){$B$};
\node[anchor={-75+180}, inner sep=0] at ($(C) +(-75:0.15)$){$C$};
\node[anchor={-75+180}, inner sep=0] at ($(D) +(-75:0.15)$){$D$};
\node[anchor=north, inner sep=0] at (0,-0.15){$E$};

\draw (A) -- (B) -- (C) -- (D) -- cycle;
\draw (A) -- (E);
\draw (D) -- (E);

\draw node[anchor=east, inner sep=0, font=\footnotesize] at ($($(A)!0.5!(E)$) +(-0.15,0)$){$4\sqrt{3}$};

%A right-angle mark is drawn at D.
\coordinate (U) at ($(D)!3mm!45:(C)$);
\draw[dash dot] (U) -- ($(D)!(U)!(C)$);
\draw[dash dot] (U) -- ($(D)!(U)!(A)$);

%A right-angle mark is drawn at E.
\coordinate (V) at ($(E)!3mm!45:(D)$);
\draw[dash dot] (V) -- ($(E)!(V)!(D)$);
\draw[dash dot] (V) -- ($(E)!(V)!(A)$);

\draw[draw=blue] ($(A) +(-90:0.7)$) arc (-90:-60:0.7);
\node[anchor=west, rotate=-75, inner sep=0, font=\footnotesize] at ($(A) +(-75:0.8)$){$30^{\circ}$};

\end{tikzpicture}

\end{document}

• It depends. \footnotesize is not an absolute size in pts (and pts are not absolute either, of course). Rather, it is relative to the default font size for the document. There is no default font size for nodes generally. If you just say \tikz{\node {whatever};} you'll get the default size which, again, will depend on your document and the context within that document. – cfr Jan 26 '16 at 3:55
• Just write \begin{tikzpicture}[font=\small], or when you are using \usepackage{anyfontsize} you can write \begin{tikzpicture}[font=\fontsize{20}{8}\selectfont]. – Giorgi Jan 26 '16 at 3:56
• @Giorgi If \footnotesize is too big, \small will only be worse, surely? – cfr Jan 26 '16 at 3:57
• – Torbjørn T. Jan 26 '16 at 5:57
• 1) No idea about the skip value. 2) same way you would implement \small etc. I think, i.e. \node[anchor=-75, inner sep=0,font=\fontsize{x}{y}\selectfont] at ($(A) +({-75+180}:0.15)$){$A$};, or put it in the node text itself. – Torbjørn T. Jan 28 '16 at 14:41

There is no answer to the question as stated. Not only is a pt relative to the font, but the meaning of commands such as \footnotesize depends on the class and, typically, on the font size option if the class offers the option of different sizes.

There is no default font size for nodes independent of everything else i.e. only in the sense that there is a default size for normal text etc. It picks up the document defaults and is context-sensitive.

amsart.cls uses 10pt by default and defines it in the following way

\DeclareOption{10pt}{\def\@mainsize{10}\def\@ptsize{0}%
\def\@typesizes{%
\or{5}{6}\or{6}{7}\or{7}{8}\or{8}{10}\or{9}{11}%
\or{10}{12}% normalsize
\or{\@xipt}{13}\or{\@xiipt}{14}\or{\@xivpt}{17}%
\or{\@xviipt}{20}\or{\@xxpt}{24}}%
\normalsize \linespacing=\baselineskip
}


\footnotesize is defined as \Small which is defined as the fourth of the text sizes i.e. {8}{10}. So 8pt font with a 10pt baseline skip.

I have no idea why this is supposed to be helpful information.

• I saw a comment from Frank Mittelbach in a response to another post. He said that there is a chapter in The LaTeX Companion book discussing fonts available in LaTeX. So, knowing something about font selection is helpful. Probably, I will just use the commands \tiny, \scriptsize, and \small to specify fonts. You said that \footnotesize is defined as \Small. Why would there be two commands to typeset the same font? (Is \Small the same as \small?) – Adelyn Jan 28 '16 at 14:11
• Also, knowing that the unit of pt is relative to the font and the class may be relevant - maybe not in coding but in comments in posts about font selection. I want to at least give the pretense that I know what I am talking about. – Adelyn Jan 28 '16 at 14:11
• \footnotesize is a standard size. \Small is specific to the AMS classes. \small is different, I believe. I suspect the double-naming is for historical reasons and to make sure standard LaTeX code does something appropriate i.e. it doesn't break if you switch to amsart from article. – cfr Jan 28 '16 at 20:27