15 · Text size, style, blinking elements and Readability

Web 2.0 Services

Items that flash or blink at a certain rate can cause seizures and should be avoided. They can also be very distracting and make other elements on a page hard to read. Complex small text and serif fonts can also make text harder to read for some people with cognitive learning disabilities and specific learning differences including dyslexia. The language used needs to be understandable for all users including those who have been deaf since birth or for whom English is not their first language. The language of the page can be programmatically determined.


This test has 4 possible outcomes.

0% Any blinking or flashing content that flashes more than three times in one second. Site unreadable.
33% Variable between serif and sans-serif. Fonts smaller than equivalent to 10pt. Overly complex language used.
67% Some serif text. Majority of text is larger than equivalent to 10pt.
100% Sans-serif fonts used in all body content (excludes headings). Regular font size (12pt equivalent or larger) throughout and reasonable layout.


The results of this test are taken into account when calculating accessibility scores for the following disabilities.


The following technique may come in handy when running this test.


This test aims to provide coverage of the following sections of best practice.

Document Section Heading
WCAG 2.0 2.3 Do not design content in a way that is known to cause seizures. More Info
WCAG 2.0 3.1 Make text content readable and understandable. More Info