WCAG 2.0 Success Criterion 1.4.8 clearly specifies that to achieve AAA conformance level, Reading content in a single line should not exceed 80 characters for non-CJK (Chinese Japanese & Korean) characters.

But the paragraphs which wrote the same stuff has more than 111 characters in a single line including space. (Space is also a character: ASCII code 32) Even if we omit the space, The character count is way over 80. So what is the deal here? Am I missing something?

Is there any mention of the line length requirements for AA or A?

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4 Answers 4


The recommended way to implement this is using relative units in em. If you check the page you have mentioned above, the <body> max-width is set at 50em, very easily within AAA conformation.

Note that this technique does not require authors to use CSS to limit the width of lines of text to less than 80 characters in the default view. Rather, the recommendation to use relative measurements in CSS layouts helps to ensure that authors do not set column widths in such a way that makes it impossible for users to view content with line lengths of 80 characters or less.

(Source: W3.org)


The phrase "Lines should not exceed 80 characters or glyphs" occurs in the section "Intent of this Success Criterion". The actual text of the Success Criterion says:

1.4.8 Visual Presentation: For the visual presentation of blocks of text, a mechanism is available to achieve the following: (Level AAA)

  1. Foreground and background colors can be selected by the user.

  2. Width is no more than 80 characters or glyphs (40 if CJK).

  3. Text is not justified (aligned to both the left and the right margins).

  4. Line spacing (leading) is at least space-and-a-half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing.

  5. Text can be resized without assistive technology up to 200 percent in a way that does not require the user to scroll horizontally to read a line of text on a full-screen window.

Source: Understanding WCAG 2.0, SC 1.4.8

At first glance, this could be seen as more prescriptive than the original quotation: "is no more than" instead of "should not exceed".

However, the preamble includes the phrase "a mechanism is available to achieve" where "mechanism" is a "key term" defined at the bottom of that page as:

process or technique for achieving a result

Note 1: The mechanism may be explicitly provided in the content, or may be relied upon to be provided by either the platform or by user agents, including assistive technologies.

Note 2: The mechanism needs to meet all success criteria for the conformance level claimed.

One "mechanism" (provided by my Windows 10 platform) is to resize the browser window. If that is done, the site seems reasonably responsive and re-flows the text to match the window, allowing you to choose your own maximum width:

enter image description here


FWIW, it's extremely rare for anyone to take the line-length criterion seriously. I've been trying to encourage people I work with to control line-lengths, but it's not always clear how to do it, especially when controlling line-lengths results in uncontrolled whitespace.

I find it very disappointing that the WCAG doesn't follow their own advice here, but I think part of the reason is that no one has yet defined how to comply and achieve good outcomes.


So what is the deal here? Am I missing something?

I think so:

Lines should not exceed 80 characters or glyphs

Should. It's not an edict.

  • 1
    Being picky, the "Success criterion" says "Width is no more than 80 characters or glyphs (40 if CJK).". It is the "Intent of this Success Criterion" that includes "should not" (and it's not immediately clear that they use that term in the same way RFCs use SHOULD NOT and MUST NOT).
    – TripeHound
    Jul 18, 2019 at 13:40

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