Posted on by Peter

Methods for measuring text readability

Content is often overlooked when working with a web site to increase accessibility. Even if your web site follows all W3C recommendations it will still be inaccessible if your content is difficult to comprehend. Let’s have a look at how you can measure text readability in english, spanish, swedish, danish and french to get a feel for the readability of your content.

In this article we will have a look at how you can test your content to see give a brief overview of formulas for measuring readability as well as an online tool to measure readability for your texts.

Content is commonly overlooked when working with a web site to increase accessibility. Even if your web site follows all W3C recommendations it will still be inaccessible if your content is difficult to comprehend. As previously mentioned here and elsewhere you can do a lot to increase accessibility by working with your content.

The technical aspects of accessibility is often more easy than the content aspects. If you are reading this you probably already know how to create an accessible web site by using the W3C recommendations. You also know how to use the W3C validator to test your templates before you put them onto your live site. Content, on the other hand, varies over time and is often created by a large number of people, each with their own personal style of writing. It is also more difficult to test using an automated tool.

Measuring readability of a text

There are a number of methods to measure the readability of a text. Most of them are based on multiple correlation analysis where researchers have selected a number of text properties (such as words per sentence, average number of syllables per word etc) and then asked test subjects to grade readability of various texts on a scale. By looking at the text properties of these texts it is possible to correlate how much “words per sentence” influence readability.

Some important facts about readability measurement methods:

  1. Readability index formulas only work for a specific language.
  2. Readability does not equal understandability.
  3. A readability index score is not an exact science. For example, it does not consider disposition (paragraphs) or actual content (are the words from a specific domain?).

Having said that we can move on to testing our content.

The readability index calculator

I have created a simple tool where you can calculate a readability index score for a text of your choice. To see a comparison, please try it with a legal document such as an EULA (End user license agreement) which typically is difficult to read. The calculator uses the following formulas:

After you are done testing your own texts, come back here and read more on what you can do to increase readability of your content.

What you can do to improve readability

If you have a large web site with many editors you should make sure all of them have a basic understanding on how to write for the web. Implementing a publishing policy and making sure it is used will ensure that your visitors get a consistent style when visiting your web site. The policy could include the following guidelines:

  1. Explain abbreviations and acronyms the first time they are used (do not rely on markup alone).
  2. Provide a subset of your content in basic english or the corresponding basic version of your language. Sweden has an organization that provides training in easy-to-read swedish. Your country/language may have similar institutions.
  3. Try to keep sentences short.
  4. Avoid symbolic language (metaphors).
  5. Avoid complicated words. Make sure you are writing from your user’s point of view. Use their terminology instead of your own.
  6. Write for the web (see Seven Krug’s book Don’t Make Me Think). Writing for the web differs from writing e.g. a scientific report. Fore more information see the references section below.

References and more information

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