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Readability Checker

Paste English text into this readability checker to get six standard readability scores at once — Flesch Reading Ease, Flesch-Kincaid grade, Gunning Fog, SMOG, Coleman-Liau and the Automated Readability Index — plus word, sentence and syllable counts.

Mode Input

Heuristic syllable counts; English only. SMOG is unreliable for short text. Scores do not measure writing quality.

Result

The six readability formulas

Flesch Reading Ease — 0–100 scale, higher is easier206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)
Flesch-Kincaid grade — US school grade0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59
Gunning Fog — years of schooling; complex = 3+ syllables0.4 × (words ÷ sentences + 100 × complex words ÷ words)
SMOG — grade; built for 30-sentence samples1.043 × √(complex words × 30 ÷ sentences) + 3.1291
Coleman-Liau — grade; counts letters, not syllables0.0588 × letters per 100 words − 0.296 × sentences per 100 words − 15.8
Automated Readability Index — grade; counts letters, not syllables4.71 × (letters ÷ words) + 0.5 × (words ÷ sentences) − 21.43

All six reward the same two things: shorter sentences and shorter words. Sentences end at a period, question mark or exclamation mark followed by a space or the end of the text — so a pasted list without punctuation counts as one very long sentence. Words are runs of the letters a–z (with apostrophes); numbers are skipped. Syllables are estimated from vowel groups, with silent endings like -es and -ed trimmed, so some words are miscounted: "created" = 1, "cooperate" = 3, "every" = 3, "readability" = 5.

Heuristic syllable counts; English only. SMOG is unreliable for short text. Scores do not measure writing quality.

Worked example: the same message, rewritten

Before

Our organization is committed to delivering innovative solutions that maximize operational efficiency for customers. Following implementation, customers consistently report significant improvements in productivity and considerably reduced administrative overhead.

After

We build tools that save our customers time. After they switch, most tell us they get more done and spend less time on paperwork.

The rewrite swaps abstract nouns ("implementation", "productivity") for verbs people use ("switch", "get more done") and says who does what. It drops from 3.04 to 1.21 syllables per word, which moves every score.

Score	Before	After
Reading ease	-64.2	92.4
Flesch-Kincaid grade	25.7	3.3
Gunning Fog	31.3	8.1
SMOG (approximate)	20.3	8.8
Coleman-Liau	31.0	7.0
Automated Readability Index	24.8	4.8
Words	28	24
Sentences	2	2
Syllables per word	3.04	1.21

The "before" Reading Ease is below zero — the formula has no floor. The "after" version still gets a Gunning Fog of 8.1 and SMOG of 8.8 because "customers" and "paperwork" count as complex words in a two-sentence sample. Short samples exaggerate single words; check full pages.

How to read the Flesch Reading Ease score

Score	Difficulty	Typical text
90–100	Very easy	Short sentences, everyday words
80–89	Easy	Conversational copy
70–79	Fairly easy	Most consumer web pages
60–69	Standard / plain English	A good target for general readers
50–59	Fairly difficult	Quality newspapers, reports
30–49	Difficult	Academic and technical writing
below 30	Very difficult	Dense legal or scientific text

Using the scores well

Set a target, then edit. Around 60+ Reading Ease or grade 8 suits most public-facing writing; specialist audiences can handle more.
Fix sentences first. Splitting one 40-word sentence into two often helps more than hunting for shorter words.
Don't write to the formula. The scores can't tell whether text is accurate, well organized or even grammatical. Choppy fragments score "easy" and still confuse readers.
Keep needed terms. If your readers need the word "mortgage", use it and explain it once.

Sources: Flesch, "A New Readability Yardstick", Journal of Applied Psychology (1948); Kincaid et al., Naval Technical Training Command Research Branch Report 8-75 (1975); Gunning, The Technique of Clear Writing (1952); McLaughlin, "SMOG Grading", Journal of Reading (1969); Coleman and Liau, Journal of Applied Psychology (1975); Smith and Senter, Automated Readability Index, AMRL-TR-66-220 (1967). Checked 15 October 2026.

Which readability score should you use?

General writing: Flesch and Flesch-Kincaid

The most widely used pair, and the two that Microsoft Word reports. Flesch-Kincaid was developed for the US Navy to grade training material. Use Reading Ease for a quick "is this plain?" check and the grade for audience targets.

Health and public information: SMOG

SMOG is popular for patient leaflets and public notices because it was built to predict full comprehension rather than partial understanding, so it tends to give a higher grade. Give it at least 30 sentences.

Cross-checks: Fog, Coleman-Liau, ARI

Gunning Fog was written with business and news writing in mind. Coleman-Liau and ARI count letters instead of syllables, so they don't depend on the syllable estimate — useful when your text has many words the heuristic gets wrong.

If the scores disagree by several grades, the text usually mixes very short and very long sentences, or packs long words into otherwise short sentences. Read the longest sentences aloud first; they are almost always what pushes the scores up.

Frequently asked questions

What is a good Flesch Reading Ease score?+

Higher is easier. 60–70 is plain English that most adults read comfortably; 70–80 is fairly easy; 90+ is very easy. 30–50 is typical of academic or technical writing, and below 30 is very hard. For web pages and customer emails, aim for 60 or above.

What grade level should I write at?+

For a general audience, aim for a Flesch-Kincaid grade of about 8 or lower — that's readable for most adults, including people reading in a second language or on a phone. Grade levels are US school years, so a score of 8 means roughly 8th grade (age 13–14).

Why do the six scores give different grades?+

They measure different things. Flesch-Kincaid and SMOG count syllables, Coleman-Liau and ARI count letters, and Gunning Fog counts words of three or more syllables. On the sample above, the plain rewrite scores grade 3.3 on Flesch-Kincaid but 8.1 on Gunning Fog, because a few three-syllable words weigh heavily in two short sentences. Look at the trend across scores, not one number.

Can the Flesch Reading Ease score be negative?+

Yes. The formula has no floor, so very long sentences full of long words go below zero. The jargon-heavy sample on this page scores -64.2. Likewise grade levels can exceed 12 — a grade of 25.7 just means "far harder than needed", not a real school year.

How does it count sentences and syllables?+

A sentence ends at a period, question mark or exclamation mark followed by a space or the end of the text. Syllables are estimated by counting vowel groups with a few rules for silent endings, which is fast but imperfect: "created" counts as 1 and "cooperate" as 3. Over a few hundred words the errors mostly even out.

Why is SMOG marked approximate?+

SMOG was designed for samples of 30 sentences. The checker scales your text to that length, so on a paragraph or two it can swing a lot. Use it on longer pieces, and lean on Flesch-Kincaid for short ones.

Does it work for languages other than English?+

No. All six formulas were calibrated on English, and the syllable counter only recognizes the letters a–z. Text in other languages will produce numbers, but they don't mean anything.

What is the Flesch-Kincaid formula?+

Flesch-Kincaid grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. Flesch Reading Ease uses the same two ratios, but higher means easier: 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Both reward short sentences and short words, which is why they usually move together.

How can I make my writing easier to read?+

Shorten sentences, swap long words for everyday ones, and write to "you" in the active voice. The "After" rewrite in the example above says the same thing as the original in plainer words: Flesch Reading Ease rises from -64.2 to 92.4 and the Flesch-Kincaid grade falls from 25.7 to 3.3. Fix the hardest sentences first rather than chasing a target number.

How much text do I need for an accurate score?+

Use at least 100 words — a few paragraphs if you can. On a sentence or two, one long word or one missing period can move the grade by several levels. For long documents, checking a few representative sections separately shows where the hard parts are better than one overall score.

Is my text sent anywhere?+

No. The scores are calculated in your browser, and your text is never uploaded or stored — safe for drafts, contracts and unpublished work.