Readability Formulas
Free readability assessment tools to help you write for your readers
Reading Levels | Grade Levels | Word Usage | Reader Profiles

Linsear Write Readability FormulaThe Linsear Write Readability Formula is an algorithm designed to measure the readability of English texts. Created by John O’Hayre in the early 1960s for the U.S. Air Force, the formula initially helped evaluate their technical manuals to ensure their personnel could easily understand them.

Unlike other readability formulas that rely on sentence length and word length, O’Hayre focused more on syntax and word complexity, particularly the number of syllables in a word. Simple words (< 3 syllables) are those that most adults can readily understand, while complex words (> 3 syllables) require a higher level of vocabulary.

The formula is as follows:


Linsear Write Readability Formula

$$\frac{[(100 – (\frac{100 \times n_{wsy<3}}{n_{w}})) +
(3 \times \frac{100 \times n_{wsy>=3}}{n_{w}})]}{(100 \times
\frac{n_{st}}{n_{w}})}$$

where \(n_{wsy<3}\) = the number of words with less than 3 syllables, and
\(n_{wsy>=3}\) = the number of words with 3-syllables or more.


To score a text manually:

  1. Choose a 100-word sample from the text.
  2. Classify Words Based on Syllables:
    • 1 syllable = score of 1.
    • 2 or more syllables = score of 3.
  3. Add the Scores: total the scores for all the words.
  4. Calculate the Grade Level: Divide by 2, and subtract a little bit depending on the result.

The final score correlates to a U.S. grade level. A score of 11 means 11th grade readers; a score of 15 means a college graduate or a professional in a specialized field.

Linsear Write Readability Formula Results

Linsear Write is widely used to score technical writing, like scientific documents or engineering manuals.

  1. It Looks at Words, Not Just Sentences: It looks at the complexity of individual words based on their syllables. In technical writing, writers often use many difficult words, specialized jargon, and industry-speak. Syllable count can help score how hard technical words are to understand.

    Example: in the sentence “The configuration of molecular structures is fascinating,” other formulas might just see a long sentence. Linsear Write looks at words like “configuration” and “molecular,” recognizing their complexity by examining the syllables.

    Example: in a sentence like “Thermodynamics involves the transformation of energy within systems,” another formula might count word length instead of syllables. This formula focuses on the complexity of words like “thermodynamics” and “transformation,” providing a more accurate reading level.

  2. It Can Be Adjusted for Different Readers: Technical texts are usually meant for people with special knowledge in a field. Linsear Write can help adjust the text to match the reading ability of readers, making sure it’s not too simple or too hard.

    Example: If an engineering document is written for technicians, Linsear Write can help adjust sentences like “The torque must be applied at 45 degrees to the horizontal plane” to suit the technicians’ reading level.

  3. It Works with Complex Sentences: Technical writings often have tricky sentence structures. Linsear Write looks at individual words instead sentence length, giving a more detailed picture of how complex the writing is.

    Example: In a sentence like “When designing a hydraulic system, taking into account the pressure, flow rate, and temperature is vital,” other tools might see this as overly complex due to its length. The formula focuses on words like “hydraulic” and “temperature,” offering a more nuanced view of the text’s complexity.

Linsear Write Scores Hard Words in Text
Linsear Write Scores Hard Words in Text

Linsear Write is a useful tool in the right context. By understanding how it works and where it’s best applied, you can decide if it’s the right choice for your reading or writing needs. You can use our Readability Scoring System to score texts with Linsear Write.