Readability checker
Flesch Reading Ease, Flesch–Kincaid grade level and four more readability scores, calculated as you type.
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| Flesch–Kincaid Grade US school grade needed. Aim for 8 or below for email. | — |
|---|---|
| Gunning Fog Index Years of education; penalises 3+ syllable words. | — |
| SMOG Index Grade level from polysyllables; common in health writing. | — |
| Coleman–Liau Index Grade level from letters per word, not syllables. | — |
| Automated Readability Index Grade level from characters per word. | — |
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- Syllables / word
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- Complex words
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- Reading time
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How the Flesch score is built
Rudolf Flesch’s 1948 formula uses only two things: how long your sentences are and how long your words are. Drag them and watch which one costs you more.
Difficult · roughly College reading level · Flesch–Kincaid grade 11.9
Notice the weights: adding 0.1 syllables per word costs 8.5 points, the same as adding more than 8 words to every sentence. Swapping “utilise” for “use” moves the score more than you’d expect.
Flesch Reading Ease score table
| Score | Difficulty | Roughly | Typical of |
|---|---|---|---|
| 90–100 | Very easy | 5th grade | Comics, children’s books |
| 80–89 | Easy | 6th grade | Conversational email |
| 70–79 | Fairly easy | 7th grade | Popular fiction, good web copy |
| 60–69 | Plain English | 8th–9th grade | Newspapers, clear business writing |
| 50–59 | Fairly difficult | 10th–12th grade | Specialist reports |
| 30–49 | Difficult | College | Academic journals |
| 0–29 | Very difficult | College graduate | Legal contracts, insurance policies |
The formulas
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)], where complex words have three or more syllables.
SMOG = 1.043 × √(polysyllables × 30 ÷ sentences) + 3.1291
Each formula has its own page with a calculator that also accepts manual counts: Flesch–Kincaid grade level, Flesch Reading Ease, Gunning Fog, SMOG, Coleman–Liau and ARI.
Readability formulas measure surface features, not meaning. A short sentence full of jargon can still score well, so pair the score with the jargon translator and your own judgement.
Questions people ask
What is a good Flesch Reading Ease score?
For business email and web copy, 60 or higher (plain English). 70–80 is easy to read for most adults. Reports for specialists can sit in the 50s. Scores under 30 are typical of legal and academic text.
What is the difference between Flesch Reading Ease and Flesch–Kincaid Grade Level?
They use the same two inputs (words per sentence and syllables per word) with different weights. Reading Ease gives a 0–100 score where higher is easier. The Flesch–Kincaid Grade Level, developed for the US Navy in 1975, converts the result to a US school grade where lower is easier.
How is readability calculated here?
Your text is split into sentences and words in your browser, syllables are estimated with a vowel-group rule, and six standard formulas are applied: Flesch Reading Ease, Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI. Syllable counting is an estimate, so scores can differ by a point or two from other tools.
What grade level should business writing be?
Grade 8 or lower for emails and anything customers read. Plain language guidance from the US federal government and the UK Government Digital Service both recommend writing for a broad audience, and even expert readers process simpler text faster.
What does a readability score of 60 mean?
A Flesch Reading Ease of 60 is the start of the “plain English” band, roughly 8th–9th grade. Most adults read it comfortably; it is a good minimum for business email and web pages.
Can I check the readability of a PDF?
Yes. Press “Upload file” above the text box and choose a PDF or a screenshot. An AI model extracts the text, then every score is calculated in your browser as usual.
How do I improve my readability score?
Shorten sentences (aim for an average of 15–20 words) and choose shorter words: “use” not “utilise”, “help” not “facilitate”, “about” not “with regard to”. The sentence length checker and wordiness checker on this site target exactly those two inputs.