Readability Tests and Formulas
by
Kalli Bravos
| Jan 14, 2010
Flesch Reading Ease 
Flesch Reading Ease = 206.835 - (1.015 * (Words / Sentences)) - (84.6 * (Syllables / Words))
| Score | Notes |
| 90-100 | Very Easy (Easily understood by an average 11-year old student) |
| 80-90 | Easy |
| 70-80 | Fairly Easy |
| 60-70 | Normal (Easily understood by 13 to 15 year old students |
| 50-60 | Fairly Difficult |
| 30-50 | Difficult |
| 0-30 | Very Difficult (best understood by college graduates) |
Flesch-Kincaid Readability Test - Wikipedia, the free encyclopedia Gunning Fog The Gunning Fog Index was developed by Robert Gunning in 1952. The index is an indication of how many formal years of education one requires to comprehend the text.
Gunning Fog = 0.4 * ((Words / Sentence) + 100 ( Complex Words / Words))
A Complex Word has three or more syllables, not including proper nouns, familiar jargon or compound words, or common suffixes such as -es, -ed, or -ing as a syllable.
Gunning fog index - Wikipedia, the free encyclopedia
Coleman-Liau The Coleman-Liau Index is a readability test designed by Meri Coleman and T. L. Liau in 1967. Similar to the ARI it is based upon characters instead of Syllables.
Coleman-Liau Index = (5.89 * (characters / words)) - (29.5 * (Sencences/Words)) - 15.8
Standard Formula
Simplified Formula
Coleman-Liau Index - Wikipedia, the free encyclopedia
FORCAST Focuses on functional literacy, questionnaires, forms, text that is not in narritive form. Readability is determined on the number of single syllable words (not number of sentences and their length). Formula is strictly not to be used for assessing primary age reading materials.
GL = 20 - (N/10)
(Based on a sample text of 150 words)
GL = Grade Level
N = Number of monosyllabic words in the sample text.
FORCAST READABILITY FORMULA
Fry Graph It is sometimes used for regulatory purposes, such as in healthcare, to ensure publications have a level of readability that is understandable and accessible by a wider portion of the population.
1. Randomly select three separate 100 word passages. (Count every word including proper nouns, initializations, and numerals.)
2. Count the number of sentences in each 100 word sample (estimate to nearest tenth).
3. Count the number of syllables in each 100 word sample. (Each numeral is a syllable. For example, 2007 is 4 syllables and one word.)
4. Plot the average sentence length and the average number of syllables on the graph.
5. The area in which it falls is the approximate grade
Fry readability formula - Wikipedia, the free encyclopedia
New Dale-Chall Based on the average sentence legnth and the number of unfamiliar words (words not in the Dale-Chall Familiar Word List). Normally used to assess upper elementary through secondary materials. One of the most accurate Readability formulas.
RGS = (0.1579 x DS) + (0.0496 x ASL) + 3.6365
RGS : Reading Grade Score
DS : Dale Score, or % of words not on Dale-Chall list of 3,000 common words
ASL : average sentence length (the number of words divided by the number of sentences)
| Score | Notes |
| 4.9 - | Grade 4 and Below |
| 5.0 to 5.9 | Grades 5 - 6 |
| 6.0 to 6.9 | Grades 7 - 8 |
| 7.0 to 7.9 | Grades 9 - 10 |
| 8.0 to 8.9 | Grades 11 - 12 |
| 9.0 to 9.9 | Grades 13 - 15(College) |
| 10 + | Grades 16 +(College Graduate) |
Powers-Sumner-Kearl The Powers-Sumner-Kearl Formula is a revised Gunning Fog Index. Most often used in evaluating text indended for use in primary grades (up to the third grade level) and is based on words, syllables and total number of sentences.
GL = 0.0778(ASL) + 0.0455(NS) – 2.2029
GL = US Grade Level
ASL = Average Sentence Length
NS = Number of Syllables
(Sample Passage of around 100 words)
THE POWERS-SUMNER-KEARL READABILITY FORMULA
Kane Requires 400 tokens (word and math tokens)
Formula I
Predicted Readability = .23X - .53Y + 61.88
Formula II
Predicted Readability = -0.15A + 0.10B -0.42C - 0.17D + 35.52
A = words not on Dale list
B = number of changes from word token to math token and vice cersa
C= number of different mathematics symbols not on the 80% mathematics list plus # of different math symbols not on the 90% Symbols list
D = Number of Question Marks
X = number of mathematics words no on the 80% mathmematics list
Y = number of different words with three or more syllables
Unfortunately, I was unable to find the mathematics or symbols list.
Kane, R. B., Byrne, M. A., & Hater, M. A. (1974). Helping Children Read Mathematics. New York: American Book Company.
Handbook of reading research By P. David Pearson, Rebecca Barr, Michael L. Kamil, Peter B. Mosenthal Bormuth Index Based on a count of characters rather than syllables. The formula was designed to evaluate more academic documents (ie school textbooks). Uses the Dale-Chall Familiar Words List
Bormuth Grade Level = .886593 - (AWL x 0.03640) + (AFW * .161911) - (ASL x 0.21401) - (ASL x 0.000577) - (ASL x 0.000005)
BGL : Bormuth grade level score or Bormuth readability score
AWL : average word length or number of characters per word (number of characters divided by the number of words)
AFW : average familiar words per word (the number of words in the original Dale-Chall list of 3,000 simple words divided by the number of words)
ASL : average sentence length in words or average number of words in sentence (number of words divided by the number of sentences)
Also called Degrees of Reading Power (DRP), but uses a slightly adapted Formula
Readability = .886593 - .083640(Letters/Words) + .161911 (DLL / Words)^3 - 0.021401(Words/Sentences) + .000577 (Words/Sentences)^2 - .000005(Words/Sentences)^3
DRP = (1 - Readability) * 100
DLL = Dale Long List words
Bormuth Grade Level Readability Score, other reading scores
Handbook of reading research By P. David Pearson, Rebecca Barr, Michael L. Kamil, Peter B. Mosenthal
The Principles of Readability - William H. DuBay
Raygor Readability Estimate The Raygor Estimate Graph is a readability metric for English text, developed by Alton L. Raygor (1977). The U.S. grade level is calculated by the average number of sentences and number of long words ( >= 6 characters). These averages are plotted onto a specific graph where the intersection of the average number of sentences and the average number of letters/word determines the reading level of the content. Note that this graph is very similar to the Fry Readability Formula's graph. This graph is primarily used in secondary education to help classify teaching materials and books into their appropriate reading groups.
Use a 100-word passage from the selection. Use multiple if passage is long
Count the number of sentences in each passage. Count a half sentence as .5.
Count the number of words in each passage containing six or more letters.
Find the point on the Raygor Estimate Graph.
Raygor Readability Estimate - Wikipedia, the free encyclopedia
Linsear Write Linsear Write is a readability metric for English text, purportedly developed for the United States Air Force to help them calculate the readability of their technical manuals. The result is the approximate Grade level of the writing.
(Easy Words + (Hard Words * 3) / Sentences
Hard Words have 3 or more syllables
Easy Words have 1 or 2 syllables
If answer > 20 then divide by 2
If answer <=20 subtract 2 then divide by 2
Based on 100 word sample
Linsear Write - Wikipedia, the free encyclopedia Strain Index Strain Index, which is based on the following assumptions:
1. The longer the sentence, the greater the strain.
2. The standard sentence has 17 words.
3. All syllables are equal ('ash', 'lash', 'slash' and 'splash').
The Strain Index can be calculated in three easy steps:
1. Choose the first three sentences.
2. Count the number of syllables in the three sentences (S3).
3. Divide S3 by 10.
| Score | Notes |
| 5.1 and Under | very easy to read |
| 15.3 and Over | very difficult to read |
STRAIN INDEX: A NEW READABILITY FORMULA - Nirmaldasan
Fernandez-Huerta The Huerta Reading Ease is a Modified Flesch Reading Ease for Spanish Texts.
Huerta Reading Ease = 206.84 - (0.60 * P) - (1.02 * F)
(Using 100 word chunks of text)
P = Number of syllables per 100 words
F = Number of sentences per 100 words
How is the Huerta Reading Ease score calculated?
A user has submitted a "correction" to the Huerta Reading Ease formula. You can find it at Linguist List. Thanks to Gwillim Law of Measurement, Inc. for pointing this out.