Writer's Workbench

Writers Workbench Style Sheet Readability Scores Formulae

The Style Analysis analyzes the surface characteristics of the writing style of a document. It prints various readability grades and length of words, sentences, and paragraphs. It can, also, further locate sentences with certain characteristics.

Numbers are counted as one-syllable words. A sentence is a sequence of words that start with capitalized words and end with a full stop, double colon, question mark, or exclamation mark. A single letter followed by a dot is considered an abbreviation, so it does not end a sentence. Various multi-letter abbreviations are recognized so that they are not confused with the end of a sentence.  The end of a paragraph is identified wherever the <Enter> key has been pressed in Microsoft Word.


The Kincaid Formula has been developed for Navy training manuals, that ranged in difficulty from 5.5 to 16.3. It is probably best applied to technical documents because it is based on adult training manuals rather than school book text. Dialogs (often found in fictional texts) are usually a series of short sentences, which lowers the score. On the other hand, scientific texts with many long scientific terms are rated higher, although they are not necessarily harder to read for people who are familiar with those terms.

The Kincaid formula -
(AVSY*11.8) + (AVW*.39) - 15.59

AVSY = The average number of syllables per word and
AVW = the average number of words in sentences


The Automated Readability Index is typically higher than Kincaid and Coleman-Liau, but lower than Flesch.

The Automated Readability Index (Auto) formula -

(AVL*4.71) + (AVW*.5) - 21.43

AVL = the average number of letters per word and
AVW = the average number of words in sentences


The Coleman-Liau Formula usually gives a lower grade than Kincaid, Automated Readability Index, and Flesch (when applied to technical documents).

The Coleman-Liau formula -

(AVL * 5.89) - (ADJS * .3) - 15.8

AVL = the average number of letters per word and
ADJS = (100 * Number of sentences) / Number of Words in the Composition


The Flesch reading easy formula was developed by Flesch in 1948, and it is based on school texts covering grade 3 to 12.  It is wide spread, especially in the USA, because of good results and simple computation. The index is usually between 0 (hard) and 100 (easy); standard English documents average approximately 60 to 70.

The Flesch formula -

206.835 (AVSY * 84.6) - (AVW  * 1.015)

where:

AVSY = The average number of syllables per word and

AVW = the average number of words in sentences and, based upon that number (findex), the number outside of the parentheses (fgrad) is calculated as:

if (findex < 30)

      fgrad = 17

else

      if (findex > 100)

            fgrad = 4

      else

            if (findex > 70)

                 fgrad = (100-findex)/10 +5

            else

                 if (findex > 60.)

                     fgrad  = (70-findex)/10+8

                 else

                     if (findex >50)

                          fgrad = (60-findex)/5+10

                     else

                          fgrad = (50-findex)/6.66 +13

Adapted to WWB 8.0 (circa 2001) from: Cherry, L.L.; Vesterman, W.: Writing Tools The STYLE and DICTION programs, Computer Science Technical Report 91, Bell Laboratories, Murray Hill, N.J. (1981), republished as part of the 4.4BSD User's Supplementary Documents by O'Reilly.

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Last modified 07/26/16