Readability CalculatorFlesch Reading Ease, grade level and the exact sentences to fix
Paste any text to get six standard readability scores, a consensus grade level and a highlighted copy that shows which sentences and words make it hard to read.
Uses the published Flesch (1948), Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI formulas. See plain language guidelines from the US government
Updated October 24, 2026
| Formula | Score | What it measures |
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Your text, highlighted
What is a readability calculator?
A readability calculator scores how easy a text is to read using formulas based on sentence length and word length. The best known is Flesch Reading Ease: 206.835 − 1.015 × words per sentence − 84.6 × syllables per word. Scores of 60–70 are plain English, suitable for most web content; higher is easier.
How to check the readability of your writing
- Paste at least 100 words. Paste body text only, without navigation or code. Headings on their own line are treated as separate sentences.
- Choose your audience. A good score for patient information is different from a good score for an engineering whitepaper. The tool compares your result with the right range.
- Read the gauge and the grade. Flesch Reading Ease gives the headline score; the consensus grade averages five grade-level formulas so one quirky formula cannot skew the result.
- Fix the highlighted sentences first. Red sentences run past 30 words, yellow ones past 20. Splitting two or three of these usually moves the score more than any other change.
Readability formulas explained
Rudolf Flesch, 1948. Scores run roughly 0–100; higher is easier. Plain English for adults sits around 60–70.
Kincaid and colleagues, 1975, for the US Navy. The result is a US school grade, so 8.0 means an eighth-grader should follow it.
Robert Gunning, 1952. “Complex” means three or more syllables; this tool leaves out hyphenated compounds.
G. Harry McLaughlin, 1969. Popular for health materials because it predicts full comprehension rather than partial.
L = letters per 100 words, S = sentences per 100 words. It counts letters instead of syllables, which makes it stable for software to calculate.
The Automated Readability Index, 1967. Like Coleman–Liau, it avoids syllable counting.
About syllable counting: software estimates syllables from vowel groups, so results can differ by a point or two between tools. Formulas that use letters (Coleman–Liau, ARI) avoid this, which is why the consensus grade averages both types.
Worked example: the sample text
The sample in the calculator has 118 words in 7 sentences, an average of 16.9 words per sentence and 1.63 syllables per word.
- Flesch Reading Ease = 206.835 − 1.015 × 16.9 − 84.6 × 1.63 = 52.1, which is fairly difficult (roughly 10th–12th grade).
- Flesch–Kincaid Grade = 10.2, and the consensus of five grade formulas is 11.7.
- One 38-word sentence in the second paragraph does most of the damage. Rewritten as three short sentences (“However, many websites still publish content full of hard terms. Their sentences wander between loosely linked ideas. Paragraphs never seem to end, so visitors work far harder than they should.”), the whole sample jumps to 67.5, plain English, without losing a single idea.
What is a good readability score?
| Flesch score | Difficulty | Approximate school level | Good fit for |
|---|---|---|---|
| 90–100 | Very easy | 5th grade | Children’s content, simple instructions |
| 80–89 | Easy | 6th grade | Consumer and conversational copy |
| 70–79 | Fairly easy | 7th grade | Patient information, product pages |
| 60–69 | Plain English | 8th–9th grade | Most blogs, guides and web pages |
| 50–59 | Fairly difficult | 10th–12th grade | B2B, finance and professional audiences |
| 30–49 | Difficult | College | Technical documentation, academic writing |
| 0–29 | Very difficult | College graduate | Legal and scientific papers |
Health content needs extra care
The US National Library of Medicine and health-literacy guidance generally advise writing patient materials at about a 6th–8th grade reading level. As a pharmacist writing patient-facing content, I treat SMOG as the main check here, because it estimates the level needed for full understanding.
Does readability affect SEO?
Google does not use readability formulas as a ranking factor. Clear writing still matters for search, because its helpful-content guidance rewards pages that satisfy people, and readers who understand a page quickly are more likely to stay, trust it and return.
How to improve your readability score
One idea per sentence
Split at “and”, “which”, “while” and “because”. Two 15-word sentences read far faster than one 30-word sentence.
Choose the short word
“Use” not “utilise”, “help” not “facilitate”, “about” not “approximately”. Each swap removes syllables without losing meaning.
Write in active voice
“We tested 40 tools” is shorter and clearer than “40 tools were tested by our team”.
Keep paragraphs short
Two to four sentences per paragraph suits screens, especially on mobile, where long blocks of text look heavier.
Define jargon once
Technical terms are fine when your readers expect them. Explain each one the first time and the rest of the page reads easily.
Don’t chase 100
An extremely high score can sound childish to expert readers. Aim for your audience’s range, not the maximum.
Related SEO calculators
Readable copy is one part of a page that ranks and converts. These tools cover the rest of the pre-publish checklist.
Readability questions, answered
For most websites, 60–70 is a good target, which Flesch described as plain English. Health and consumer content often aims for 70 or higher, while technical and academic writing usually scores between 30 and 50.
Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Shorter sentences and shorter words both raise the score.
Both use sentence length and syllables per word. Reading Ease gives a 0–100 score where higher is easier, while Flesch-Kincaid converts the same inputs into a US school grade, where lower is easier.
Most guidance suggests about an 8th-grade level for general web audiences. Patient health information is often written at a 6th–8th grade level, while B2B and technical content can go higher if readers expect it.
No. Google does not use readability formulas to rank pages. Clear writing still supports SEO because people understand and trust the content faster, which is what Google's helpful-content guidance aims to reward.
Mainly because they count syllables and sentences differently. Software estimates syllables from vowel groups, and sentence detection varies around abbreviations and headings. Differences of one or two points are normal.
SMOG estimates the years of education needed to fully understand a text by counting words of three or more syllables. It is widely used for health and patient information because it targets complete comprehension.
An average of 15–20 words per sentence works well for web content. Mix lengths for rhythm, and break up any sentence longer than about 25–30 words.
No. All analysis runs in your browser. The text you paste is never sent to a server or saved.
At least 100 words, ideally several hundred. Very short passages give unstable results, and SMOG was designed for samples of 30 sentences.
Manzoor Ahmad
Web developer & SEO specialist · 13+ years
I have spent 13+ years in web development and SEO and more than 9 years writing health and supplement content as a pharmacist, where plain language is not optional. I run every patient-facing and SEO article through these same formulas before publishing. Read my full profile.
Published and last reviewed: October 24, 2026
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Sources & references
- Flesch, R. (1948). A new readability yardstick. Journal of Applied Psychology, 32(3).
- Kincaid, J. P. et al. (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).
- US General Services Administration. Federal plain language guidelines.
- MedlinePlus (US National Library of Medicine). How to write easy-to-read health materials.
- Google Search Central. Creating helpful, reliable, people-first content.
Readability formulas estimate difficulty from surface features such as sentence and word length. They cannot judge accuracy, structure or tone. Treat scores as a guide alongside your own editing and, where possible, feedback from real readers.