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


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



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


  • 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
    Jan 3 '21 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} Sep 6 '10 at 15:46

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. Sep 7 '10 at 4:34

In mathematical environment you may use \boldsymbol

here is my suggestion:


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.

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