# What are the possible dimensions / sizes / units LaTeX understands?

I know there are different ways of expressing sizes or dimensions in LaTeX such as points (pt), inches (in) and ex.

As some commands, such as \hspace understand all of them, I would like to have a reference or complete list of possible dimensions or sizes including a description of what they mean.

• The definitive reference is the TeXbook by Donald Knuth; the source of which is freely available. Commented Jan 17, 2012 at 16:59

From the plain TeX reference:

• pt: Point
• pc: pica (12 pt)
• in: inch (72.27 pt)
• bp: Big point (72 bp = 1 in)
• cm: Centimeter
• mm: Millimeter
• dd: Didot point (1157 dd = 1238 pt)
• cc: cicero (12 dd)
• sp: Scaled point (65536 sp = 1 pt), the smallest TeX unit
• ex: Nominal x-height
• em: Nominal m-width

Available in math mode:

• mu: math unit, 1 em = 18 mu, where em is taken from the math symbols family, various lengths are derived from it (thinspace, thickspace, etc.)

Additionally available in pdfTeX and LuaTeX:

• px: "pixel", the dimension given to the \pdfpxdimen primitive; default value is 1 bp, corresponding to a pixel density of 72 dpi

The meanings of the various points are described here:

• Thanks a lot. Could you expand a little on Didot points and the meaning of the nominal in ex and em? Commented Jan 17, 2012 at 14:34
• It is worth to note that "sp" is the smallest TeX unit and that it cannot be subdivided further. Thus any length in TeX is an integer multiple of "sp". Commented Jan 17, 2012 at 14:39
• em: It is M-width
– user2478
Commented Jan 17, 2012 at 14:39
• pdftex and luatex have also the px unit, whose value can be changed on a per document basis (default 1px = 1bp). Commented Jan 17, 2012 at 14:41
• there's also the mu -- math unit (1 em = 18 mu, where em is taken from the math symbols family). this can be used only in math mode. Commented Jan 17, 2012 at 14:49

I made visual overview for all units available in TeX. Including a comparison and the definitions/conversions.

The complete code and PDFs (EN, DE; b/w, color) are available at GitHub: https://github.com/tweh/tex-units

• Oh my.... (+1) Some people do have too much time :D
– user31729
Commented May 23, 2016 at 15:36
• @ChristianHupfer: Actually too much work to not procrastinate ;-)
– Tobi
Commented May 23, 2016 at 15:39
• I believe you have mislabeled the PostScript point: tex.stackexchange.com/questions/21758/…
– Alan
Commented Jul 3, 2016 at 20:29
• @Alan: Indeed … thanks! Don’t know where this mistake came from …
– Tobi
Commented Jul 3, 2016 at 20:44
• Amazing. The github source has a PDF version. Super useful, thanks! Commented Feb 8, 2021 at 10:17