TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

To make Latin-letter variables bold I can use e.g. \mathbf{a}, but while putting Greek letters or symbols such as \nabla inside \mathbf doesn't cause any errors or warnings, it also doesn't do anything else.

What is the best way to make bold math symbols, in particular Greek letters and \nabla?

share|improve this question
warning: if the default computer modern fonts are used, the weight of bold lowercase greek will not appear as bold as that of bold lowercase roman, and it isn't. default bold math (\mathbf} with computer modern fonts uses the font cmbx* which is an extended font. \boldsymbol or bm use the only cm font that is usually available in bold, cmmib10, which is not an extended font. thus the bold greek letters are indeed not as "bold" as the roman. – barbara beeton Aug 26 '12 at 21:45

10 Answers 10

up vote 178 down vote accepted

The AMS Short Math Guide recommends the \boldsymbol and \pmb commands (and suggests that you use the bm package for the former to get a more powerful version than provided by amsmath).

share|improve this answer
I would vote for the bm package surely! – yo' Aug 26 '12 at 11:11
It looks like that \boldsymbol (from amsbsy) is obsolete and \bm (package bm) should be used (ref). – Atcold 2 days ago

In my experience, there is no single best way. Therefore Table 327 on page 113 of the Comprehensive LaTeX Symbol List comes in really handy.

bold math overview

share|improve this answer
ehm bm ehm. Can you underline "experience" with facts about problems of bm? – yo' Feb 21 '13 at 17:32
@tohecz No, unfortunately not. I don't have the particular example anymore. I just happened to stumble on this old question and I thought I'd add this list since I did encounter tricky cases where it was helpful to be able to try different approaches. bm should surely be the first package to try though. I will add examples where it doesn't work when it ever happens again. – Christian Feb 21 '13 at 17:48
You can always use \boldsymbol{}, but this will only work if there exists a bold version of the symbol in the current font. – sinner Jan 15 '15 at 4:44
In my personal experience, \pmb (the faked bold) is the most universal – Szczypawka May 11 '15 at 16:57
@Szczypawka Most universal ... probably. But also a measure of last resort. – Christian May 11 '15 at 18:06

With unicode-math you can use \symbf{<characters>} which works for both Greek and Latin letters. (In versions of unicode-math older than 0.8 the \symXXX macros didn't exist, but you could \mathbf{<characters>} directly.)

Compile with xelatex or lualatex.

\( AaBb∇αβγ \) \par
\( \symbf{AaBb∇αβγ} \) \par
\( \symrm{AaBb∇αβγ} \)

enter image description here

share|improve this answer
Does not work for me. Bold latin symbols appear OK, but greek ones (from nabla onwards) don't show. I have XITS Math font correctly installed on my system (linux), and I compiled this MWE with both xelatexand lualatex, with no luck. What am I doing wrong? – Orestes Mas May 31 at 16:44
Update to my previous comment: I managed to make it work doing the following. 1) Specify math font as \setmathfont{XITS Math} (I'm on a linux system and that is the name of the font my system reports) and 2) Adding \usepackage{bm} AFTER setting the math font. Without step 2), greek bold characters don't show up and latin bold appears to be typeset in Latin Modern Bold – Orestes Mas May 31 at 17:07
@OrestesMas There were some updates to unicode-math recently, use \symbf instead of \mathbf. – Torbjørn T. May 31 at 18:25

Another possibility is \boldmath, though I would prefer \boldsymbol of amsmath as well. \unboldmath switches back to the normal math font.

share|improve this answer
Why is \boldsymbol preferred over \boldmath? – drs May 18 '13 at 1:18
@drs \boldsymbol is included in the package amsmath, which is ubiquitous, while \boldmath is not. – glarrain Jan 9 '14 at 19:24

If you use the package bm you can do $\bm{a}=\bm{\alpha}$ etc.

share|improve this answer

While \bm and \boldmath are some good options in LaTeX, modern packages for XeLaTex can give a lot more control over the fonts from the very beginning, without the need to use commands different from the standard \mathbf that every one expects naively to work the first time one tries to write bold italic characters.

In XeLaTeX (part of TeXLive), the package fontspec gives a lot of freedom when dealing with fonts. If you want even more flexibility for mathematical input, you can try using the package unicode-math (that is built on fontspec). Nevertheless you will find the \bm and \boldsymbol traditional commands don't work. You can nonetheless specify how you want it to deal with your bold math symbols using an option while loading the unicode-math package. \usepackage[bold-style=ISO]{unicode-math} will give the recommended italic bold math symbols for both greek and latin characters, while \usepackage[bold-style=TeX]{unicode-math} will give upright latin characters. This is explained in the unicode-math documentation .

This minimal working example:

%run this with XeLaTeX!!
\setmathfont{XITS Math}


This is common math $O(\log n)+O(\lambda,\,\epsilon)$

This is bold and italic $\mathbf{O(\log n)}+\mathbf{O(\lambda,\,\epsilon)}$ where it must :)


enter image description here

share|improve this answer
Welcome to TeX.SX. – Claudio Fiandrino Mar 27 '13 at 10:55
Welcome to TeX.sx! Rather than posting identical answers to different questions, you should post your answer at the most appropriate place (here: tex.stackexchange.com/a/104524/510) and (as soon as you have 50 rep) add comments with links at other places. – lockstep Mar 27 '13 at 10:55

In order to have just one command for both bold text and bold math, one can use the solution suggested on LaTeX Community (/forum/viewtopic.php?t=10866&f=44#p42084, link not allowed). Editing this solution slightly in order to incorporate the bm package, one could use the following.

share|improve this answer

My solution (the one that I use) is the \mathversion{bold} and \mathversion{normal} commands.

This piece of code is not a MWE —however, it shows how to use them:

\section{Behavior of $f$ as a function of $\lambda$}\label{sec:1}

And now, imagine that \mathversion{bold}\textbf{we want to put some
text in bold, and that this text contains some inline equation such as

Hope it helps.

share|improve this answer

Another option:

\newcommand{\boldm}[1] {\mathversion{bold}#1\mathversion{normal}}

There is a normal symbol, $p_1$. Now, a bold symbol: {\boldm $p_2$}. It works!



Rendered example of using bold and math in LaTeX

share|improve this answer

Use the command \boldsymbol{YOUR_SYMBOL}

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.