# MathJax Font Support¶

MathJax version 3 currently supports only one font, the MathJax TeX font. Version 2 provides the following fonts:

• MathJax TeX (default)
• STIX General
• Asana Math
• Neo Euler
• Gyre Pagella
• Gyre Termes
• Latin Modern

MathJax contains customized webfont versions of these fonts. In particular, these customized versions are split over several files to minimize the page load.

MathJax 3 will support these fonts in a future version.

## Use of Other Fonts¶

In version 2 of MathJax, it was difficult to adjust the fonts in use (once loaded), or to replace individual or collections of characters being used. For example, switching the variables and function names to use a sans-serif font rather than the standard serifed font is quite difficult in version 2. The structure of the font data in version 3 has been completely redesigned to help make such changes easier to make.

Since browsers do not provide APIs to access font metrics, MathJax has to ship with the necessary font data; this font data is generated during development and cannot be determined easily on the fly. The tools for creating the data needed by MathJax have not yet been created for version 3 (the data for the MatahJax TeX font was converted from the version 2 format by hand). These tools are high on the list for inclusion in the next version of MathJax, which should provide the additional fonts missing from the initial release of version 3. At that point, the details of how to mix-and-match font characters, and how to create the data files for your own fonts for use in MathJax, will be provided.

## Character fallbacks¶

No font contains a suitable glyph for every character specified in the Unicode standard. When MathJax encounters a character that isn’t in the font that it is using, it will fall back to other fonts in a variety of ways.

First, MathJax enhances Unicode coverage of its default TeX fonts, e.g., combining two double integrals U+222C when a quadruple integral U+2A0C is used. However, this cannot create every character specified in Unicode. Next, MathJax will run through a fallback chain within the configured fonts (e.g., upright Greek will be substituted with italic Greek).

Finally, when all else fails, MathJax will ask the browser to provide the glyph from a system font. Since in that final case, MathJax will not have the necessary data on the glyph’s bounding box, MathJax will guess these metrics. When run in a browser, MathJax will be able to determine the character’s width, but not its height and depth, so it will use default values these metrics. Measuring the width can negatively affect the rendering speed, and guessing the height and depth can reduce the quality of the resulting output. When used on a server or in a command-line application, MathJax won’t even be able to determine the width, and that has an even more serous consequences for the layout, in general. Thus it is best to use only the characters that are in the MathJax fonts when using server-side rendering.