The New Dale-Chall Readability Formula has improved readability scoring, building upon the foundation laid by its predecessor. The (original) Dale-Chall Readability Formula, developed by Edgar Dale and Jeanne Chall in the 1940s, became a standard in scoring text readability. It helped match reading materials to the learners’ reading abilities, ensuring their understanding and promoting further reading. The formula is based on difficult words and average sentence length. While the original formula was useful, it did not capture syntactic complexity and word familiarity.
The New Dale-Chall Readability Formula addresses the original formula’s shortcomings. Chall improved linguistic and syntactic features, along with an expanded and updated list of familiar words. The Chall Word List, as it is known, identifies words that may challenge readers.
The formula scores a text using these steps:
- Word Identification: The formula identifies words absent in the word list. These words are considered “difficult words” because readers might find them challenging.
- Difficult Words Count: The number of difficult words is tallied.
- Sentence Count: A longer “average sentence count” could imply more intricate sentences, impacting the text’s overall readability. This factor extends the complexity assessment beyond just vocabulary.
- Familiar Words Adjustment: The number of difficult words is divided by the total word count, and the result is multiplied by 100 to give the percentage of difficult words.
The new formula is as follows:
$$64 – (0.95 \times 100 \times \frac{n_{wd}}{n_{w}}) – (0.69 \times ASL)$$
The New Dale-Chall Readability Formula
Interpreting the Score
Score | Grade Level | Reading Level | Ages |
>= 57 | 1 | Very Easy | 5-6 years old |
>= 53 | 2 | Easy | 7-8 years old |
>= 49 | 3 | Fairly Easy | 9-10 years old |
>= 44 | 4 | Standard | 11-12 years old |
>= 39 | 5-6 | Fairly Difficult | 13-14 years old |
>= 33 | 7-8 | Difficult | 15-16 years old |
>= 27 | 9-10 | Very Difficult | 17-18 years old |
>= 21 | 11-12 | Extremely Difficult | 18+ years old |
>= 21 | College | Professional | 20+ years old |
- Content Relevance: Text should matter to the reader. Even simple writing may confuse if it discusses unfamiliar or dull topics. But, a complex topic can grip a reader if it speaks to their interests.
- Reader Motivation: The reader’s eagerness to learn affects understanding. An excited reader will try harder to grasp tough content. Engaging and inspiring text is crucial.
- Learning Styles: Everyone absorbs information differently. Some lean towards images, others prefer words or sounds. These preferences play a part in judging a text’s complexity.
- Background Knowledge: Familiarity with the subject shapes the reader’s grasp of the text. Unknown terms or concepts can stump them, no matter how readable the text is.
- Cultural References: Texts often use idioms or references known only to certain cultures. These can hinder understanding for others.
- Text Structure: The layout of a text affects its readability. Clear headings, bullet points, diagrams, and logical flow can aid comprehension.
- Language Nuances: Tricky language devices like irony or sarcasm can make comprehension harder. These aren’t covered by readability formulas but can influence understanding.
While text assessment tools can be useful, writers still need to review the overall text’s complexity and the target audience’s needs.
At ReadabilityFormulas.com, you can score your text using both the original and updated versions of Dale-Chall, or select from a range of syntactic, word-based, and graph-based formulas.