# Unit in LaTeX

### Units

<table><thead><tr><th width="152">Abbreviation</th><th>Value</th></tr></thead><tbody><tr><td>pt</td><td>approx 0.3515 mm</td></tr><tr><td>cm</td><td>a millimeter</td></tr><tr><td>mm</td><td>a centimeter</td></tr><tr><td>in</td><td>= 2.54 cm</td></tr><tr><td>ex</td><td>roughly the height of an 'x' (lowercase) in the current font (it depends on the font used)</td></tr><tr><td>em</td><td>roughly the width of an 'M' (uppercase) in the current font (it depends on the font used)</td></tr></tbody></table>

### Built-in lengths

<table><thead><tr><th width="202"></th><th></th></tr></thead><tbody><tr><td><code>\baselineskip</code></td><td>Vertical distance between lines in a paragraph</td></tr><tr><td><code>\columnsep</code></td><td>Distance between columns</td></tr><tr><td><code>\columnwidth</code></td><td>The width of a column</td></tr><tr><td><code>\evensidemargin</code></td><td>Margin of even pages, commonly used in two-sided documents such as books</td></tr><tr><td><code>\linewidth</code></td><td>Width of the line in the current environment.</td></tr><tr><td><code>\oddsidemargin</code></td><td>Margin of odd pages, commonly used in two-sided documents such as books</td></tr><tr><td><code>\paperwidth</code></td><td>Width of the page</td></tr><tr><td><code>\paperheight</code></td><td>Height of the page</td></tr><tr><td><code>\parindent</code></td><td>Paragraph indentation</td></tr><tr><td><code>\parskip</code></td><td>Vertical space between paragraphs</td></tr><tr><td><code>\tabcolsep</code></td><td>Separation between columns in a table (tabular environment)</td></tr><tr><td><code>\textheight</code></td><td>Height of the text area in the page</td></tr><tr><td><code>\textwidth</code></td><td>Width of the text area in the page</td></tr><tr><td><code>\topmargin</code></td><td>Length of the top margin</td></tr></tbody></table>

With these built-in commands, we can:

* Use these lengths as unit, like `0.25\textwidth`
* Modify them using `\setlength`
