Next: \setlength, Up: Lengths [Contents][Index]
TeX and LaTeX know about these units both inside and outside of math mode.
pt
Point, 1/72.27 inch. The conversion to metric units is 1point = 2.845mm = .2845cm.
pc
Pica, 12 pt
in
Inch, 72.27 pt
bp
Big point, 1/72 inch. This length is the definition of a point in PostScript and many desktop publishing systems.
cm
Centimeter
mm
Millimeter
dd
Didot point, 1.07 pt
cc
Cicero, 12 dd
sp
Scaled point, 1/65536 pt
Two other lengths that are often used are values set by the designer of
the font. The x-height of the current font ex, traditionally the
height of the lowercase letter x, is often used for vertical
lengths. Similarly em, traditionally the width of the capital
letter M, is often used for horizontal lengths (there is also
\enspace
, which is 0.5em
). Use of these can help make a
definition work better across font changes. For example, a definition
of the vertical space between list items given as
\setlength{\itemsep}{1ex plus 0.05ex minus 0.01ex}
is more
likely to still be reasonable if the font is changed than a definition
given in points.
In math mode, many definitions are expressed in terms of the math unit mu given by 1 em = 18 mu, where the em is taken from the current math symbols family. See Spacing in math mode.