The HTML5 test score is only an indication of how well your browser supports the upcoming HTML5 standard and related specifications. It does not try to test all of the new features offered by HTML5, nor does it try to test the functionality of each feature it does detect. Despite these shortcomings we hope that by quantifying the level of support users and web developers will get an idea of how hard the browser manufacturers work on improving their browsers and the web as a development platform. Please note that the HTML5 test is not affiliated with the W3C or the HTML5 working group.
The score is calculated by testing for the many new features of HTML5. Each feature is worth one or more points. Apart from the main HTML5 specification and other specifications created the W3C HTML Working Group, this test also awards points for supporting related drafts and specifications. Some of these specifications were initially part of HTML5, but are now further developed by other W3C working groups. WebGL is also part of this test despite not being developed by the W3C, because it extends the HTML5 canvas element with a 3d context.
The test also awards bonus points for supporting audio and video codecs and supporting SVG or MathML embedding in a plain HTML document. These test do not count towards the total score because HTML5 does not specify any required audio or video codec. Also SVG and MathML are not required by HTML5, the specification only specifies rules for how such content should be embedded inside a plain HTML file.
Please be aware that the specifications that are being tested are still in development and could change before receiving an official status. In the future new tests will be added for the pieces of the specification that are currently still missing. The maximum number of points that can be scored is 400 at this moment, but this is a moving goalpost.