Analyze the readability level of your text
Understanding Readability Formulas
Learn about the different formulas used to assess readability and how to interpret their scores.
Flesch Reading Ease
The Flesch Reading Ease score is one of the most widely used readability formulas. Higher scores indicate material that is easier to read, while lower scores indicate more difficult text. The formula considers sentence length and syllable count.
Score Interpretation
Higher scores indicate greater readability.
Flesch-Kincaid Grade Level
The Flesch-Kincaid Grade Level formula translates the Reading Ease score into a U.S. school grade level. It tells you the academic grade a person needs to have completed to understand your content. The formula uses the same metrics (sentence length and syllables) but yields a grade-level score.
Score Interpretation
Lower scores indicate greater readability.
Gunning Fog Index
The Gunning Fog Index estimates the years of formal education a person needs to understand the text on the first reading. It considers sentence length and the percentage of complex words (words with three or more syllables).
Score Interpretation
Lower scores indicate greater readability.
Coleman-Liau Index
The Coleman-Liau Index is based on characters rather than syllables, making it ideal for computerized assessment. It estimates the U.S. grade level required to understand the text. Unlike other formulas, it focuses on character count, which is easier to calculate automatically.
Score Interpretation
Lower scores indicate greater readability.
SMOG Index
The SMOG Index (Simple Measure of Gobbledygook) estimates the years of education needed to understand a text. It is particularly accurate for checking health messages and is often used in healthcare materials. SMOG focuses on polysyllabic words and is calculated using a sample of 30 sentences.
Score Interpretation
Lower scores indicate greater readability.
Automated Readability Index
The Automated Readability Index (ARI) focuses on character count per word instead of syllables, similar to the Coleman-Liau Index. This makes it easier to calculate programmatically. It provides an approximate representation of the U.S. grade level needed to understand the text.
Score Interpretation
Lower scores indicate greater readability.
Linsear Write Formula
The Linsear Write Formula was developed for the U.S. Air Force to calculate the readability of technical manuals. It counts 'easy words' (two syllables or less) and 'hard words' (three syllables or more) in a 100-word sample, then applies a formula to calculate the grade level.
Score Interpretation
Lower scores indicate greater readability.
FORCAST Formula
The FORCAST formula was developed specifically for assessing technical documents and forms, rather than continuous text with full sentences. It only uses a count of one-syllable words in a 150-word sample to determine the grade level. 'N' is the number of single-syllable words in the sample.
Score Interpretation
Lower scores indicate greater readability.
Powers-Sumner-Kearl Formula
The Powers-Sumner-Kearl Formula was designed to assess the readability of elementary-level texts and children's books. It is typically used for content aimed at grades 1-6 and becomes less accurate for higher grade levels.
Score Interpretation
Lower scores indicate greater readability.
Why Different Formulas Give Different Results
Each readability formula measures different aspects of text complexity. Some focus on sentence length, others on word length or syllable count. For a more accurate assessment, consider the average of multiple formulas and tailor the formula to your specific audience and content type.
How to Improve Readability
- Use shorter sentences (15-20 words on average)
- Choose simpler, common words
- Use active voice instead of passive voice
- Break long paragraphs into smaller chunks
- Use bullet points and lists for complex information
- Use headings to organize information
What is a good Flesch score?
Flesch Reading Ease runs from 0 to 100, and a higher score means easier text. In How to Write Plain English, Rudolf Flesch set 60 as the minimum for plain English and asked for at least 80 in conversational writing for consumers.
| Score | School level |
|---|---|
| 90–100 | Grade 5 |
| 80–90 | Grade 6 |
| 70–80 | Grade 7 |
| 60–70 | Grades 8 to 9 |
| 50–60 | Grades 10 to 12 |
| 30–50 | College |
| 0–30 | College graduate |
Flesch fitted the formula's coefficients to English texts in 1948, so a score for another language is only a rough guide.
Writing for a particular reader? Check which level they read at before you aim for a score. For length, see how many pages the text fills and how long it runs when read aloud.
How the summary sets its targets
The consumer and plain language targets follow Flesch. Grade 6 matches his score of 80 for consumer writing, and grade 9 is the top of the band he gave for his plain English minimum of 60.
Patient health information aims at grade 6, because a review in American Family Physician recommends a sixth-grade reading level or lower for patient education material.
Academic texts aim at college level, grade 16 at most, the band Flesch put between scores of 30 and 50.
The sentence map scores each sentence on its own with the grade formula of its language, Flesch-Kincaid outside Polish and Russian, and marks sentences four or more grades above the target.
Reading time assumes 238 words a minute, the average silent reading rate for non-fiction in Brysbaert's 2019 meta-analysis.
Scores for texts in other languages
LIX adds the average sentence length to the percentage of long words, those with more than six letters. RIX divides the number of long words by the number of sentences. Neither needs a syllable count, which is how Björnsson could use LIX to compare newspapers in 11 languages.
LIX = words ÷ sentences + 100 × long words ÷ words; RIX = long words ÷ sentences
For the syllable formulas, syllables are counted from the vowel letters of each language. English keeps its own spelling rules.
Questions about readability scores
What is a good Flesch Reading Ease score?
Aim for 60 or more for plain language and 80 or more for conversational writing aimed at consumers. Those are the minimums Rudolf Flesch set in How to Write Plain English.
What reading level should patient information be written at?
Sixth grade or lower. A review in American Family Physician recommends that level for patient education material.
Does the checker work for texts that are not in English?
Yes, with limits. It counts words and syllables in the language of the text and adds LIX and RIX, which count letters instead of syllables. The English grade formulas still run, so read them as a rough guide. Polish texts also get FOG-PL and the Pisarek index, and Russian texts get Oborneva's adaptation of Flesch. Japanese texts get counts only.
Is my text uploaded anywhere?
No. The analysis runs in your browser and the text is not sent to a server. It is kept in this browser's local storage so the detailed report can open it.
Sources
- Flesch, R. (1948). A new readability yardstick. Journal of Applied Psychology, 32(3), 221–233.
- Flesch, R. (1979). How to Write Plain English, chapter 2.
- Kincaid, J. P., Fishburne, R. P., Rogers, R. L., & Chissom, B. S. (1975). Derivation of new readability formulas for Navy enlisted personnel.
- McLaughlin, G. H. (1969). SMOG grading: a new readability formula. Journal of Reading, 12(8), 639–646.
- Smith, E. A., & Senter, R. J. (1967). Automated Readability Index.
- Coleman, M., & Liau, T. L. (1975). A computer readability formula designed for machine scoring. Journal of Applied Psychology, 60(2), 283–284.
- Powers, R. D., Sumner, W. A., & Kearl, B. E. (1958). A recalculation of four adult readability formulas. Journal of Educational Psychology, 49(2), 99–105.
- Björnsson, C. H. (1983). Readability of newspapers in 11 languages. Reading Research Quarterly, 18(4), 480–497.
- Anderson, J. (1983). Lix and Rix: variations on a little-known readability index. Journal of Reading, 26(6), 490–496.
- Safeer, R. S., & Keenan, J. (2005). Health literacy: the gap between physicians and patients. American Family Physician, 72(3), 463–468.
- Brysbaert, M. (2019). How many words do we read per minute? A review and meta-analysis of reading rate. Journal of Memory and Language, 109, 104047.