# Conventions for formatting scientific units?

I would appreciate some guidance on how to format units that incorporate SI, molecules, and text.

Right now I am formatting the letters in chemicals or names as 'text' and the SI units, sub/super scripts and numbers in math.

For example, I would appreciate feedback on how to format the following for publication:

• meter squared leaf area per meter squared of ground: $m^2$leaf$m^{-2}$leaf
• grams carbon: $g$C
• carbon dioxide CO$_2$

This previous question about [what package should be used to typeset units] is similar, except that I am not convinced that I need to add another package like siunitx (publishers request that I minimize use of extra packages).

Thanks!

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But packages like »mhchem« and »siunitx« would make life much easier in this regard. To minimize packages means to me not to load unnecessary packages. – Thorsten Donig Dec 10 '10 at 18:55
@Thorsten That is a good point. I guess I'll go ahead and take the plunge. – David LeBauer Dec 10 '10 at 19:20
better not to anger the editor :P – Timtico Dec 10 '10 at 19:33

Use the SIunits package. Note that SI units are to be typeset in roman type, not italics! And please don't mix information and units. “g C” (with a thin space) can mean only one thing, namely the product of the units gram and Coulomb. Mixing in information like C for carbon with the units is a cardinal sin. A major point of standardised units with a standardised notation is disambiguation – if you see an SI unit in a paper far from your own speciality you should still be able to understand what it means.

Please refer to the style guides at the NIST SI units home page for further details.

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Thanks for the review and for pointing out my cardinal sin. When working with information, I often find it useful to combine units and information (e.g. to keep everything straight in a calculation), but is is the proper approach when reporting a calculation to include all of the required information by using letters with subscripts rather than numbers? – David LeBauer Dec 17 '10 at 15:55
I am not sure what is “proper”, but use of subscripts or explanatory text should be okay. Just so long as it cannot be confused with the units. – Harald Hanche-Olsen Dec 17 '10 at 16:38
The NIST documents are indeed very helpful. 1 vote up. – yCalleecharan Jan 13 '11 at 18:05

The siunitx package provides the of command that can be used in this way:

\si{\micro\mol\of{CO$_2$}\per\meter\squared\second\}


It will add the information as a subscript (or other formats specified by the qualifier-mode)

Here is an example:

\documentclass{article}
\usepackage{siunitx}
\begin{document}
\si{\gram\of{CO$_2$}}
\end{document}


produces:

Here are other options (from the siunitx documentation

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