Version 3 is now the current version of MathJax. This document is for version 1.

MathJax Output Formats

Currently, MathJax can render math in two ways:

  • Using HTML-with-CSS to lay out the mathematics, or
  • Using a browser’s native MathML support.

These are implemented by the HTML-CSS and NativeMML output processors.

If you are using one of the combined configuration files, then this will select one of these output processors for you. If the config file ends in _HTML, then it is the HTML-CSS output processor, and if it ends in _HTMLorMML, then the NativeMML output processor will be chosen if the browser supports it, otherwise HTML-CSS output will be used.

If you are performing your own in-line or file-based configuration, you select which one you want to use by including either "output/HTML-CSS" or "output/NativeMML" in the jax array of your MathJax configuration. For example

jax: ["input/TeX","output/HTML-CSS"]

would specify TeX input and HTML-with-CSS output for the mathematics in your document.

The HTML-CSS output processor produces high-quality output in all major browsers, with results that are consistent across browsers and operating systems. This is MathJax’s primary output mode. Its major advantage is its quality and consistency; its drawback is that it is slower than the NativeMML mode at rendering the mathematics. (The HTML-CSS processor has not yet been optimized for speed, so you can expect some improvement in the future. Note that IE8 in “IE8 standards mode” is an order of magnitude slower than any other browser when processing math through the HTML-CSS output processor; see HTML-CSS with IE8 below for some strategies to deal with this.)

The NativeMML output processor uses the browser’s internal MathML support (if any) to render the mathematics. Currently, Firefox has native support for MathML, and IE has the MathPlayer plugin for rendering MathML. Opera has some built-in support for MathML that works well with simple equations, but fails with more complex formulas, so we don’t recommend using the NativeMML output processor with Opera. Safari, Chrome, Konqueror, and most other browsers don’t support MathML natively, but may in the future, since MathML is part of the HTML5 specification.

The advantage of the NativeMML output Processor is its speed, since native MathML support is much faster than using complicated HTML and CSS to lay out mathematics, as the HTML-CSS output processor does. The disadvantage is that you are dependent on the browser’s MathML implementation for your rendering, and these vary in quality of output and completeness of implementation. MathJax may rely on features that are not available in some renderers (for example, Firefox’s MathML support does not implement some of the named widths, such as negativethinmathspace). The results using the NativeMML output processor may have spacing or other rendering problems that are outside of MathJax’s control.

Automatic Selection of the Output Processor

Since not all browsers support MathML natively, it would be unwise to choose the NativeMML output processor unless you are sure of your audience’s browser capabilities. MathJax can help with that, however, since a number of its combined configuration files will select NativeMML output when the browser supports it, and HTML-CSS output otherwise. These are the configuration files that end in _HTMLorMML.

If you are doing your own configuration, there is a special configuration file that you can include that will choose between NativeMML and HTML-CSS depending on the browser in use. To invoke it, add "MMLorHTML.js" to your configuration’s config array, and do not include an output processor in your jax array; MathJax will fill that in for you based on the abilities of your user’s browser.

config: ["MMLorHTML.js"],
jax: ["input/TeX"]

You can customize which choice to make on a browser-by-browser basis or a global basis. See the config/default.js file or the Configuring MMLorHTML section for further details. As an example, this configuration tells MathJax to use HTML-CSS output rather than native MathML support for Firefox:

<script type="text/x-mathjax-config">
    MMLorHTML: { prefer: { Firefox: "HTML" } }
<script type="text/javascript"

With this configuration, MathML output will be used only for IE with the MathPlayer plugin (Firefox is the only other browser to have native MathML support that is sufficient for use with MathJax). Note, however, that a user can employ the MathJax contextual menu to select the other renderer if he or she wishes.

MathJax produces MathML that models the underlying mathematics as best it can, rather than using complicated hacks to improve output for a particular MathML implementation. When you make the choice to use the NativeMML output processor, you are making a trade-off: gaining speed at the expense of quality and reliability, a decision that should not be taken lightly.


Internet Explorer 8 has at least eight different rendering modes in which it can operate, and that are triggered by the DOCTYPE of the document being viewed. Its “quirks” mode is its fastest mode, and its “IE8 standards” mode is its slowest. This is the mode triggered by strict HTML document types, and since most modern content management systems now include a DOCTYPE that activates “standards” mode, IE8 will operate in its slowest manner. This is particularly apparent when MathJax is used, since IE8 in standards mode runs 20 to 30 times slower than it does in its IE7 emulation mode, and 60 times slower than in quirks mode, on the sample equations page in test/sample.html.

Most users find this speed reduction unacceptable when there is much mathematics on the page. To overcome this problem, you may wish to tell IE8 to use its IE7 emulation mode rather than its IE8 standards mode. You can accomplish this by including the line

<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7">

at the top of the <head> section of your HTML documents. This lets you keep the strict DOCTYPE for validation purposes, while still managing to get reasonable performance from Internet Explorer 8. Note that this line must come at the beginning of the <head>, before any stylesheets or other content are loaded.

Alternatively, you can use the MMLorHTML configuration file described above to select NativeMML output when possible, and request that your users install the MathPlayer plugin, which will render the mathematics much more quickly.

It appears that IE9 in IE9 standards mode may perform better than IE8, but since IE9 is still in beta testing as of this writing, we have yet to see exactly what the performance of MathJax in IE9 will be like.