In $L a T e X$ there are a lot of lengths determining various dimensions of prepared documents. For example, specified dimension parameters characterize fonts, pages, or paragraphs.

[edit] Units

Below a description of available units in $L a T e X$ .

Abbreviation	Value
pt	a point is approximately 1/72.27 inch, that means about 0.0138 inch or 0.3515 mm (exactly point is defined as 1/864 of American printer’s foot that is 249/250 of English foot)
mm	a millimeter
cm	a centimeter
in	inch
ex	roughly the height of an 'x' (lowercase) in the current font (it depends on the font used)
em	roughly the width of an 'M' (uppercase) in the current font (it depends on the font used)
mu	math unit equal to 1/18 em, where em is taken from the math symbols family

Below an example that shows the difference between ex and em units.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amssymb}
\usepackage{graphicx}
 
\begin{document}
Example of a picture with different lenghts
\includegraphics[width=15ex]{lion-logo}
 
\includegraphics[width=15em]{lion-logo}
\end{document}

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[edit] Lengths

Lengths are units of distance relative to some document elements. Lengths can be changed by the command:

\setlength{\lengthname}{value_in_specified_unit}

For example, in a two-column document the column separation can be set to 1 inch by:

\setlength{\columnsep}{1in}

Below is a table with some of the most common lengths and their description

Length	Description
`\baselineskip`	Vertical distance between lines in a paragraph
`\columnsep`	Distance between columns
`\columnwidth`	The width of a column
`\evensidemargin`	Margin of even pages, commonly used in two-sided documents such as books
`\linewidth`	Width of the line in the current environment.
`\oddsidemargin`	Margin of odd pages, commonly used in two-sided documents such as books
`\paperwidth`	Width of the page
`\paperheight`	Height of the page
`\parindent`	Paragraph indentation
`\parskip`	Vertical space between paragraphs
`\tabcolsep`	Separation between columns in a table (tabular environment)
`\textheight`	Height of the text area in the page
`\textwidth`	Width of the text area in the page
`\topmargin`	Length of the top margin

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[edit] Using lengths as units

Default lengths can not only be set to any desired value, they can also be used as units to set the dimensions of other $L a T e X$ elements. For instance, you can set an image to have a width of one quarter the total text width.

\includegraphics[width=0.25\textwidth]{lion-logo}
[...]

In the command \includegraphics the width is set to 0.25 the width of the entire text area (see Inserting Images for more information about this command). You can use any length and multiply it by any factor.

Lengths in LaTeX

Contents

[edit] Units

[edit] Lengths

[edit] Using lengths as units

[edit] Further reading

[edit] Overleaf guides

[edit] LaTeX Basics

[edit] Mathematics

[edit] Figures and tables

[edit] References and Citations

[edit] Languages

[edit] Document structure

[edit] Formatting

[edit] Fonts

[edit] Presentations

[edit] Commands

[edit] Field specific

[edit] Class files