This extension provides a quick-and-easy display of the readability score of text in plain text or Markdown files when a file is opened or saved, or when the "Check readability" command is run (Ctrl + Shift + P, "Check readability").
Currently supported readability score formulas include:
Currently supported languages include:
Future plans for this extension include highlighting the text based on readability score values (eg: long sentences, difficult paragraphs, challenging words, etc.) to make it easier to see where the text could be revised.
Automated Readability Index
Text is reviewed using the Automated Readability Index formula, and calculates the approximate US grade level needed to understand the text, based roughly on the length of words in the document and the number of words per sentence.
The returned score can be from 1 to 14, and will generally represent the grade level required to understand the text. More specifically:
Text is reviewed using the Coleman-Liau index, which calculates the approximate US grade level needed to understand the text. The Coleman-Liau index relies on characters instead of syllables per word, much like the Automated Readability Index.
The returned score is an integer above 1, and will generally represent the grade level required to understand the text, with level 14 and above being suitable for a college student.
Dale-Chall Readability Formula
Using the Dale-Chall Readability Formula, the text is checked against a list of 3,000 words that fourth-grade American students should be able to reliably understand, and any words in the text that are not on that list are marked "difficult." The final score is generated taking into account the percentage of difficult words in the text and the number of long sentences.
The final score can be any number below 9.9, and corresponds roughly to the following grade levels:
Flesch Reading Ease
Using the Flesch Reading Ease formula, the text's readability score is generated in part based on the average number of words in sentences, and the average number of syllables in the words.
The returned score can be from negative numbers to 120. These can be roughly approximated to the following grade levels:
Flesch-Kincaid Grade Level
The score is calculated using the Flesch-Kincaid grade level, which determines readability based on the average number of words in sentences, and the average number of syllables in the words. That score is then translated into the approximate grade level required to understand the text.
The returned score is the approximate grade level required to understand the text; or, the number of years of education required to understand the text (especially when the formula returns a number higher than 10). Negative numbers are possible, but usually indicate the text is very easy to read.
Simple Measure of Gobbledygook (SMOG) Formula
The SMOG Formula uses the number of sentences and the number of polysyllabic words in the text to generate the approximate number of years of education needed to understand the text.
Spache Readability Formula
Using the Spache Readability Formula, the text is checked against a set list of everyday words, and any words in the text that are not on that list are marked "difficult." The final score is generated taking into account the percentage of difficult words in the text and the average sentence length.
The score returned by the formula will reflect the approximate grade level that should be able to understand the text.
The Spache readability formula is best used on texts that are targeted to younger audiences (children in or below 4th grade). For older audiences, the Dale-Chall formula will generally work better.
This extension supports the following settings:
Score can be any of the below options:
If unset, the extension will default to
Initial release of ReadabilityCheck
Add Markdown format stripping to make the wordcount/character counts more accurate, to improve score accuracy.
Update extension to add user settings options.
Fix wordcounts and word list parsing to improve accuracy for Dale-Chall, Coleman-Liau, and SMOG formulas
This extension is released under the MIT license.
This extension references the following packages released under the MIT license: