Unit in LaTeX

Units

Abbreviation	Value
pt	approx 0.3515 mm
cm	a millimeter
mm	a centimeter
in	= 2.54 cm
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)

Built-in lengths

\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

With these built-in commands, we can:

• Use these lengths as unit, like 0.25\textwidth

• Modify them using \setlength