Correct typesetting is what you would expect from an academic community. Chem.SE has always tried to be one, and we always value their standards; and our meticulous editors have always had an eye on correct typesetting; even if all that needs changing is a slanted $$M$$ that should be $$\rm M$$; because that is the standard.

But now, The Chatminators™ have sensed a dire lack of ability to typeset upright Greek letters. To cut to the chase, we need a way to easily typeset upright Greek letters. Some of the uses that come to mind(s) are:

• The $$\pi$$ in $$\pi$$-bonding, $$\pi$$-acceptors, $$\pi$$-electrons, $$p\pi\text{-}d\pi$$ etc. should be upright, not slanted. Basically any $$\pi$$ in should be upright.
• $$\alpha$$, $$\beta$$ and $$\gamma$$ radiations cause lethal cancers if not typeset upright.
• The $$\alpha$$ and $$\beta$$ stereochemical descriptors should be upright. (e.g. $$\beta$$-D-glucose)
• $$\alpha$$-hydrogens, $$\beta$$-keto esters and $$\gamma$$-lactones are crying because the regiochemical descriptors should be upright while they aren't.
• $$\eta$$ and $$\kappa$$ should both be upright in the context of transition metal complexes.
• The constant $$\pi = 3.14159265\ldots$$ should be upright to avoid confusion with a variable named $$\pi$$.1
• All units should be upright, thus neither $$3 \,\mu m$$ is acceptable nor $$\rm 3 \,\mu m$$.
1: This issue is network-wide, but to my disappointment, math.SE seemed not eager to typeset pi in any other shape than slanted.

Honestly, the commonness of the upright pi in MO-theory is enough to make a valid request for a preferably Mathjax-ical solution. But I needed more bullet points$$\ldots$$

A very easy - and user-friendly - solution is the upgreek package. The point of this meta post is to request a way to be able to typeset upright Greek letters without the need of an external source, to which a useful solution is the upgreek package. So please load this package along with Mathjax, or allow us to write upright Greek letters in some other way, using the UI available to us in chem.SE. Please make it so.

• Woot woot! The Chatminators are on the march! – bon Sep 21 '15 at 20:15
• It does not work in mathjax, but for text you can use HTML &pi; &pi; and so on. (And it obviously does not work in comments either.) – Martin - マーチン Sep 23 '15 at 1:15

This should be a feature request for MathJax developers, not for Stack Overflow developers. The upgreek package that you linked to is a LaTeX package. MathJax is not LaTeX. One does not simply add LaTeX packages to MathJax.

It's true that MathJax has several extensions, some of which implement the functionality of certain LaTeX packages (mhchem is a notable example). But there is no "upgreek" MathJax extension at present.

• You're no fun Normal. :( But anyways, I figured this out myself some time after posting this - that there are no upgreek extensions to Mathjax. And while both slanted and upright versions of uppercase Greek letters are supported, the only option for the lowercase ones is slanted, unless we use some of the user's fonts. I'll leave this post hang for "hysterical/historical reasons". – M.A.R. ಠ_ಠ Sep 21 '15 at 22:05

There are currently several feature requests open for MathJax, that explicitly mention upright greek fonts. The status is currently "A future release".

Wasysym and textcomp is also considered (via \unicode) and some more packages.

Also related at Meta.CrossValidated: Upright greek letters

Since this is nothing the StackExchange network can help with, this is .

And now let's clean up a bit ┬─┬ ノ( ^_^ノ)

As I indicated in my comment to @Normal's answer, we have both upright and slanted uppercase Greek letters with Mathjax (with upright the default option):

\begin{array}{lcl}\verb+\Lambda\Gamma\Psi+& \Longrightarrow & \Lambda \Gamma \Psi \\ \verb+\it \Lambda\Gamma\Psi+ & \Longrightarrow & \it \Lambda\Gamma\Psi\end{array}

There is currently no way to get lowercase Greek letters with Mathjax web fonts:

\begin{array}{lcl}\verb+\lambda\gamma\psi+&\Longrightarrow & \lambda\gamma\psi \\ \verb+\rm\lambda\gamma\psi+ &\Longrightarrow & \rm\lambda\gamma\psi \\ \verb+\bf\lambda\gamma\psi+&\Longrightarrow &\bf\lambda\gamma\psi \end{array}

Thus, we have to rely on fonts in the user's computer, and that's a bit of a risk. But hey, who doesn't have fonts like "Times" not installed? For that matter, here's my sandbox answer. And BTW, (╯°□°）╯︵ ┻━┻ (ノಠ_ಠ)ノ^ ┻━┻ （ノT＿T)ノ ＾┻━┻.

• The situation is a bit complex on the MathJax end. First, note that MathJax's behavior is actually identical to TeX/LaTeX with these inputs (and no extra packages). Second, even if you forced MathJax's internal representation to use boldface or normal variants (e.g., \mmlToken{mi}[mathvariant="normal"]{&#x03BB;}), you'd (probably) still get the same result. A couple of things lead to this. First, MathJax's TeX fonts do not have the relevant glyphs (just like Computer Modern which is why TeX needs packages that also provides fonts). – Peter Krautzberger Sep 28 '15 at 8:55
• Second, like all characters not covered by our TeX fonts, MathJax will follow a complex font fallback chain. By design MathJax does not always fall back all the way to system fonts (which can lead to layout glitches) but maps to similar glyphs that are in its fonts. Finally, if MathJax is set up to use locally installed fonts (which SE's configuration is), and you have STIX fonts installed, then you might see a different result from \mmlToken{mi}[mathvariant="normal"]{&#x03BB;} because ths STIX fonts cover these glyphs. – Peter Krautzberger Sep 28 '15 at 8:59