Readability Bookmarklet

This tool will show you how readable selected text is on a page. The readability guidelines are based on WCAG 2 Level AAA Conformance. Note, there is no readability requirement for WCAG 2, Level AA Conformance. The results are based on six tests.

  • Flesch Reading Ease: 60 or higher is passing
  • Grade Level Equivalencies: 9th grade (15-16 years old) or less is passing
    • Flesch-Kincaid Grade Level
    • Gunning-Fog Grade Level
    • Automated Readability Index
    • Colemane-Liau Index
    • Simple Measure of Gobbledygook (SMOG) – This test is only valid for text passages with more than 30 sentences and will not be run on shorter passages.

Automatically assessing reading levels is not always a straight forward process. Proper names and titles do not count against the reading level, but creating a script that can handle those cases is difficult. This tool currently does not try to exclude proper names.

Additionally, Web pages often have lots of single word links, like menus, which can skew the results to indicate the main content is more readable than it really is. This tool works by allowing you to either

  • select particular text in a document to analyze
  • analyze an entire document

How to Use the Tool

  1. To get the tool, add the following link to your bookmarks: Readability
    • Note, you cannot simply click the above link to make the tool work. You must add the link to your bookmarks by either dragging it to your bookmarks menu or using your browser’s context menu to add it to the bookmarks menu.
  2. When you are viewing a Web page, either
    • with your cursor, select the text you would like to analyze, then activate the tool by selecting the link in your bookmark menu
    • to analyze the entire page, simply activate the tool by selecting the link in your bookmark menu
  3. The tool will tell you the readability levels according to the six different metrics.

Note, this tool will not work on Google Docs and may not work in other WYSISYG editors.

This tool is under active development. Once you install it, you will always get the latest changes to the tool every time you run it. Any feedback you have is greatly appreciated. Please send comments to