4.3 Font sizes

The following standard type size commands are supported by LaTeX. The table shows the command name and the corresponding actual font size used (in points) with the ‘10pt’, ‘11pt’, and ‘12pt’ document size options, respectively (see Document class options).

The commands are listed here in declaration (not environment) form, since that is how they are typically used. For example.

\begin{quotation} \small
  The Tao that can be named is not the eternal Tao.
\end{quotation}

Here, the scope of the \small lasts until the end of the quotation environment. It would also end at the next type style command or the end of the current group, so you could enclose it in curly braces {\small This text is typeset in the small font.}.

Trying to use these commands in math, as with $\small mv^2/2$, results in ‘LaTeX Font Warning: Command \small invalid in math mode’, and the font size doesn’t change. To work with a too-large formula, often the best option is to use the displaymath environment (see Math formulas), or one of the environments from the amsmath package. For inline mathematics, such as in a table of formulas, an alternative is something like {\small $mv^2/2$}. (Sometimes \scriptsize and \scriptstyle are confused. Both change the font size, but the latter also changes a number of other aspects of how mathematics is typeset. See Math styles.)

An environment form of each of these commands is also defined; for instance, \begin{tiny}...\end{tiny}. However, in practice this form can easily lead to unwanted spaces at the beginning and/or end of the environment without careful consideration, so it’s generally less error-prone to stick to the declaration form.

(Aside: Technically, due to the way LaTeX defines \begin and \end, nearly every command that does not take an argument technically has an environment form. But in almost all cases, it would only cause confusion to use it. The reason for mentioning the environment form of the font size declarations specifically is that this particular use is not rare.)