Readability


What does it do?

Measure how easy the writing in this website is to understand.

Why is it important?

As a general principle, making text easier to read aids the usability of a website, which in turn makes it more likely to be used, and used successfully. Copywriting on websites is often sub-standard, and impenetrable marketing and technical jargon compromises the effectiveness of a website. One of the metrics tested (Flesch Kincaid) has become a US government standard. Many US agencies require documents or forms to meet specific readability levels; most states require insurance forms to score 40–50 on the test.

What is reading age?

Reading age measures the amount of formal education a person needs to have had (on average) to comprehend a piece of text.

For example, a reading age of 15 means a person who has been formally educated until age 15 will on average be able to understand that text.

Note that even in highly developed countries that average reading ages for the adult population are typically much lower than the 16 or 18 you might expect. For example, in the UK about half of working adults have a reading age of 11 or lower. In the US the average reading age is around 14.

How is it measured?

WebScan uses two public standards to evaluate readability of English:

  • Flesch Kincaid Reading Ease - Higher scores indicate material that is easier to read; lower numbers mark harder-to-read passages.
  • Gunning Fog Index - An indication of the number of years of formal education that a person requires in order to easily understand the text on the first reading.

These two measures are also available in Microsoft Word.

Only portions of the site containing significant text are evaluated (for example, we ignore menus, footers and so forth). Pages with very small amounts of text are also ignored (typically these say things such as 'Please wait'). All other pages are scored on a sliding scale from 0 to 10, with highly readable pages scoring 10 and virtually unintelligible pages scoring 0.

Technical explanation

For a technical explanation of Gunning Fog and Flesch Kincaid, see the respective articles on Wikipedia:

Potential problems

The test is impossible to run on non-English websites, as these metrics are specifically designed for the English language. We may eventually add comparable equivalents for other major languages. Some websites necessitate that text is more difficult to read than others (e.g. a legal paper versus a comic book). We intend to add user specified ‘ideal targets’ for readability over time.

See also testing non-English websites.

How to improve this score

Review the worst performing (i.e. hardest to read) pages for this test, and wherever possible rewrite them to be easier to understand. As a general rule, avoid jargon, complex words and keep your sentences short. Use a professional copywriter, or review the guidelines on plain English.

How to use this test effectively

Use this test to ensure your writing is pitched at the right level for your audience. Compare what the score correlates to:

Publication Average Flesch Kincaid
Reader's Digest 65
Time 52
Harvard Law Review 30

Publication Average Gunning Fog
TIME 11
Newsweek 10
Reader's Digest 9
Comic books 6

Making text readable does not have to mean dumbing it down, but there are always going to be some cases where hard-to-read is necessary (such as for legal pages).

Impact on Summary Scores

Summary Score Percentage Penalty
Accessibility Score 4.7% Penalty if below 2.2
Content Score 9.8% None
Marketing Score 1.9% None
Overall Score 3.0% None