About the Readability Score Calculator
Most people do not read online text word by word: they skim, scan and give up quickly if a page feels like hard work. Government services, health information, product instructions and marketing copy are all more effective when they are easy to read. Readability formulas give a quick, objective measure of how demanding a text is, based on how long its sentences are and how long its words are.
This readability score calculator gives the Flesch Reading Ease score and five related measures: the Flesch–Kincaid grade level, the Gunning fog index, the Coleman–Liau index, the Automated Readability Index, and an average grade level. It also shows the counts behind the scores — words, sentences, syllables and complex words — and a tip for improving the text.
How to Use the Readability Score Calculator
Paste your text into the box. The scores are most reliable with 100 words or more; very short samples can swing widely.
Remove headings, lists of links and captions if you want to score only the body text.
How the Scores Are Worked Out
Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)
Flesch–Kincaid grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59
Gunning fog = 0.4 × (words ÷ sentences + 100 × complex words ÷ words)
Coleman–Liau = 0.0588 × L − 0.296 × S − 15.8
(L = letters per 100 words, S = sentences per 100 words)
Automated Readability = 4.71 × (letters ÷ words) + 0.5 × (words ÷ sentences) − 21.43Complex words are words with three or more syllables. Syllables are estimated from the spelling of each word.
Step-by-Step Example
A text averaging 20 words a sentence and 1.5 syllables a word.
Reading ease: 206.835 − 1.015 × 20 − 84.6 × 1.5 = 59.6
Grade: 0.39 × 20 + 11.8 × 1.5 − 15.59 = 9.9That is just under plain English on the Flesch scale, and about the level of a 14 to 15-year-old reader. Cutting the average sentence to 15 words would raise the reading ease to about 64.7.
What the Flesch Scores Mean
| Reading ease | Description | Typical reader |
|---|---|---|
| 90 – 100 | Very easy | Age 11 |
| 80 – 89 | Easy | |
| 70 – 79 | Fairly easy | |
| 60 – 69 | Plain English | Age 13 – 15 |
| 50 – 59 | Fairly difficult | |
| 30 – 49 | Difficult | College |
| 0 – 29 | Very difficult | Graduate |
Most popular newspapers and websites aim for a reading ease of 60 or above. Legal documents and academic papers often score below 30.
Grade Levels
The grade-level formulas translate difficulty into the US school grade a reader would need: a grade of 8 suits a 13 to 14-year-old, and a grade of 12 a final-year high-school student. Many public bodies aim for a grade of 8 or below for information meant for everyone, because a large share of adults read most comfortably at that level, regardless of their education. Writing simply is not the same as writing for children: clear writing respects busy readers.
Why the Formulas Disagree
Each formula was designed for different material and weights things differently. The Flesch formulas count syllables; Coleman–Liau and the Automated Readability Index count letters instead, which computers once found easier; the Gunning fog index focuses on long words. Technical text full of long terms scores harder on fog than on Flesch. Look at the scores together, and at the trend when you edit, rather than treating one number as exact.
Improving Readability
Shorten sentences. Aim for an average of 15 to 20 words, with some shorter and some longer for rhythm. Split sentences joined by "and", "which" or semicolons.
Choose everyday words. Use "use" rather than "utilise", "help" rather than "facilitate" and "start" rather than "commence".
Prefer active verbs. "We will send the form" is shorter and clearer than "the form will be sent by us".
Break up the text with headings, short paragraphs and lists, which the formulas do not measure but readers notice.
Where Readability Formulas Came From
Rudolf Flesch published his Reading Ease formula in 1948, and it became widely used in journalism and advertising. In 1975, J. Peter Kincaid and colleagues adapted it into a grade level for the US Navy to assess training manuals, creating the Flesch–Kincaid grade now built into many word processors. Robert Gunning's fog index, published in 1952, came from his work helping newspapers write more clearly. The Coleman–Liau and Automated Readability indexes were designed so that machines could count letters easily, before syllable counting by computer was practical.
Limits of Readability Formulas
Formulas count, they do not understand. A text of short, simple words in short sentences can still be confusing if it is badly organised, uses jargon the reader does not know, or leaves out key information. Equally, a technical text may score as difficult yet be perfectly clear to its specialist readers. Use the scores as a warning light, then read the text as your audience would, or better still, ask someone from that audience to read it.
Understanding Your Result
Reading ease gives the Flesch Reading Ease score and its description.
Grade level gives the Flesch–Kincaid US grade level.
Other scores gives the Gunning fog, Coleman–Liau and Automated Readability scores.
Average grade averages the four grade-level scores.
Counts shows the words, sentences, syllables and complex words.
Tip suggests the quickest improvement.
When Should You Use This Calculator?
Writing web pages and blog posts.
Checking public information and health leaflets.
Editing reports for a wider audience.
Setting reading material for students.
Comparing drafts as you edit.
Common Mistakes
Scoring a very short sample.
Treating one score as exact.
Chasing a score at the expense of meaning.
Including headings and lists in the sample.
Using the formulas on languages other than English.