I know \mathcal{ABC...}, but can't bold these

6 Answers 6


You can define your own math alphabet that accesses the Computer Modern symbol font in its bold weight.



$\mathcal{A}$ $\mathbfcal{A}$


  • 1
    What does each of the arguments do? I get a bold font that is different from the mathcal in the particular article latex format, was wondering how to modify to make them consistent. I suspect that I should change cmsy by some other font.
    – Blade
    Commented Jan 3, 2021 at 21:46

You're going to need a font that contains bold calligraphic fonts. One possibility for fonts without it is to use the bm package.

  • 5
    This also works for bolding greek letters in math mode, e.g. \bm{\alpha} Commented Sep 6, 2010 at 15:46

In mathematical environment you may use \boldsymbol

here is my suggestion:


Another option is to bite the bullet and use LuaTeX with OpenType math fonts. In Context mkiv you can use


${\bf\cal abc}$

To get bold calligraphic fonts. As a bonus you get lowercase calligraphic as well. I am sure that unicode-math for lualatex has something similar.

  • 2
    Yep: \setmathfont{xits-math.otf}...$\mathbfcal{abc}$. Can be used in XeLaTeX or LuaLaTeX. Commented Sep 7, 2010 at 4:34

In unicode-math, \mathbfcal or \symbfcal.

In mathalpha, which is compatible with PDFLaTeX, \mathbcal. This gives you a nearly-comprehensive selection of all available 8-bit fonts, with a consistent interface, and scaling.

Update: Version 1.14 and higher of mathalpha changed the command to \mathbfcal. The old name is available as an alias if you give it the [oldbold] package option.


I find that \boldsymbol works (for both mathcal and greek letters!).

But I stumbled upon this question when it stopped working for me. Turns out the culprit was the breqn package; I was able to get my \boldsymbol{\mathcal{F}} to show up as a calligraphy F after removing \usepackage{breqn}.


% \usepackage{breqn}




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