Readability Score

How do I check the readability score and grade level of my writing — the Flesch Reading Ease, Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI — without uploading my text?

Open AnyTool’s Readability Score, paste any English text, and it computes the six classic readability formulas entirely in your browser, plus a consensus US grade level, the full text statistics and a plain-language verdict. It shows the Flesch Reading Ease on a 0–100 gauge (higher is easier; 60–70 is the “standard”, roughly 8th-grade band recommended for general web and SEO content), and the five grade-level formulas — Flesch–Kincaid Grade (0.39·words/sentence + 11.8·syllables/word − 15.59), Gunning Fog (0.4·[words/sentence + 100·complex÷words], complex = 3+ syllables), SMOG (1.0430·√(polysyllables·30/sentences) + 3.1291), Coleman–Liau (0.0588·L − 0.296·S − 15.8, on letters and sentences per 100 words) and ARI (4.71·chars/word + 0.5·words/sentence − 21.43) — each with its grade interpretation, then averages the five into a single consensus grade. Alongside the scores it reports the statistics the formulas are built from: words, sentences, paragraphs, syllables, characters, complex (3+ syllable) words, average words per sentence and syllables per word, the longest and over-long sentences, and reading and speaking time. A verdict translates the grade into plain language (e.g. “~8th grade — most adults can read this easily”) and you can copy a full text report. Everything is computed locally — your text is never uploaded, so it is safe for drafts and confidential content. Honest caveat: these formulas are approximations based on word + sentence length + a heuristic syllable count; they do NOT measure comprehension, accuracy, tone or whether the writing is good, they are tuned for ENGLISH (other languages mislead), and the syllable count is heuristic — use them as a rough guide and write for YOUR audience.

Computes Flesch Reading Ease + Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI, each with a grade interpretation
Gives a single consensus US grade level (the average of the five grade formulas) and a plain-language verdict
Reports full text stats: words, sentences, paragraphs, syllables, complex words, averages, longest sentence, reading & speaking time
100% client-side — your text never leaves the browser; safe for drafts and confidential content; copy a full report
Honest: formulas are English-tuned approximations of word + sentence length + heuristic syllables — not a measure of comprehension or quality

What is

A readability score is a number that estimates how hard a piece of text is to read, derived from simple surface features — chiefly average sentence length and average word length (in syllables or letters). The best-known is the Flesch Reading Ease, a 0–100 score (higher = easier) calculated as 206.835 − 1.015·(words/sentences) − 84.6·(syllables/words); a score of 60–70 is “standard” plain English, around an 8th- to 9th-grade reading level. Most other formulas output a US grade level instead: 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 = 3+ syllables; SMOG = 1.0430·√(polysyllables·30/sentences) + 3.1291; Coleman–Liau = 0.0588·L − 0.296·S − 15.8 (L = letters per 100 words, S = sentences per 100 words); and the Automated Readability Index (ARI) = 4.71·(characters/words) + 0.5·(words/sentences) − 21.43. Because they all read the same two signals, the scores usually agree and are often averaged into a consensus grade. They are deliberately simple, which makes them fast and language-agnostic to compute but also crude: they reward short words and sentences regardless of meaning, are calibrated for English, and rely on a syllable estimate, so they approximate difficulty rather than measure comprehension or writing quality.

SEO & Web

Related terms

Flesch Reading EaseFlesch–Kincaid Grade LevelGunning Fog indexSMOG indexColeman–Liau indexAutomated Readability Index (ARI)consensus grade levelsyllable count8th-grade reading level

Frequently Asked Questions

For most websites, marketing copy and SEO content, a Flesch Reading Ease of about 60 to 70 is the sweet spot — that is plain English at roughly an 8th- to 9th-grade reading level, which the average adult can read comfortably and skim quickly. On the grade-level formulas (Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau, ARI) that corresponds to a consensus grade of around 7 to 9. Writing much above that (long sentences, lots of 3+ syllable words) narrows your audience; writing far below it can feel choppy. The big exception is audience: technical documentation, legal, medical or academic writing legitimately scores higher because the precise vocabulary matters more than ease, and those readers expect it. AnyTool’s Readability Score shows the Flesch gauge, every formula, a consensus grade and a plain-language verdict so you can judge against your own audience rather than chase a single number.

For general web and SEO content, aim for a Flesch Reading Ease of about 60 to 70 — roughly an 8th- to 9th-grade reading level, which most adults can read easily. Technical, legal or academic audiences expect a higher level.

Readability formulas read just two surface signals — how long your sentences are (words per sentence) and how long your words are (syllables, letters or characters per word) — and combine them with fixed coefficients. Flesch Reading Ease = 206.835 − 1.015×(words/sentences) − 84.6×(syllables/words), giving a 0–100 score where higher is easier. Flesch–Kincaid Grade = 0.39×(words/sentences) + 11.8×(syllables/words) − 15.59. Gunning Fog = 0.4×[(words/sentences) + 100×(complex words ÷ words)], where a complex word has 3+ syllables. SMOG = 1.0430×√(polysyllables × 30/sentences) + 3.1291. Coleman–Liau = 0.0588×L − 0.296×S − 15.8, where L is letters per 100 words and S is sentences per 100 words. ARI = 4.71×(characters/words) + 0.5×(words/sentences) − 21.43. AnyTool computes all six in your browser, averages the five grade formulas into a consensus grade, and shows the underlying word, sentence and syllable counts so nothing is a black box.

Readability formulas combine average sentence length with average word length. Flesch Reading Ease = 206.835 − 1.015×(words/sentences) − 84.6×(syllables/words); grade-level formulas like Flesch–Kincaid use the same two signals with different coefficients.

Readability scores are approximations built almost entirely from how long your sentences and words are, so they capture only one dimension of difficulty. They do not measure whether your text is accurate, well-organised, persuasive, well-toned or actually understandable — you can earn a great score by chopping every sentence in half while communicating nothing, and a dense but brilliantly clear technical passage can score “difficult”. They are also calibrated for English (other languages produce misleading numbers) and depend on a heuristic syllable counter that has no pronunciation dictionary, so unusual words can be off by a syllable, and SMOG in particular wants 30+ sentences to be reliable. Treat the score as a directional signal — a prompt to check for over-long sentences and needlessly complex words — not as a grade on your prose. AnyTool states this prominently and pairs the numbers with the raw statistics so you can interpret them sensibly.

No. They only measure word and sentence length plus a syllable estimate. They do not assess comprehension, accuracy, tone, structure or whether the ideas are clear and correct — you can score well while saying nothing useful.

The Readability Score tool is 100% client-side: the text you paste is split into words, sentences and syllables and run through the readability formulas with ordinary JavaScript on your device — nothing is fetched, uploaded, logged or stored on a server, and no CDN is called for processing. That makes it safe for analysing unpublished drafts, confidential reports or internal documents without exposing them. It updates as you type, works offline once cached as a PWA, supports dark mode and a mobile layout with a sticky Sample / Copy report bar, and lets you copy a full plain-text report of every score and statistic. The same engine (textStatsEngine) is shared with sibling tools, but each runs locally in your browser.

No. The text is tokenized and scored entirely in your browser with plain JavaScript and is never uploaded, logged or stored, so it is safe for drafts and confidential documents. It also works offline once cached.

Readability Score

Paste any English text and the tool computes the six classic readability formulas in your browser — Flesch Reading Ease (0–100 gauge) plus the Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI grade levels — averages the five grade formulas into a consensus US grade, and reports the full text statistics (words, sentences, paragraphs, syllables, complex words, averages, longest sentence, reading & speaking time) with a plain-language verdict. 100% client-side; your text is never uploaded; honest that the formulas are English-tuned approximations of word + sentence length + heuristic syllables and do not measure comprehension or quality.

Features

Flesch Reading Ease on a 0–100 gauge with its band (very easy → very difficult) and approximate school level
Flesch–Kincaid Grade, Gunning Fog, SMOG, Coleman–Liau and ARI, each with a grade interpretation, plus a consensus grade
Full text statistics: words, sentences, paragraphs, syllables, complex (3+ syllable) words, averages, longest sentence, reading & speaking time
Plain-language verdict (e.g. “~8th grade — most adults can read this easily”) and a copyable text report
100% client-side; honest that scores are English-tuned approximations of length, not a measure of comprehension or writing quality

PriceFree

CategorySEO & Web

PlatformAll (browser-based)

PrivacyYour text is tokenized and scored locally and never uploaded; no server, no CDN for processing

Input: Paste or type any English text, Load a sample paragraph

Output: Flesch Reading Ease gauge + band, Six readability formulas with grade interpretations, Consensus grade level + plain-language verdict, Full text statistics, Copyable text report

Detailed Explanation

How It Works

What the Readability Score Tool Computes

Readability Score is a 100% client-side tool that estimates how hard a piece of English text is to read. The user pastes any text and, as they type, the tool computes the six classic readability formulas and the underlying text statistics in the browser. It shows the Flesch Reading Ease on a 0–100 gauge — 206.835 − 1.015·(words/sentences) − 84.6·(syllables/words), where higher is easier and 60–70 is the “standard” plain-English band around an 8th- to 9th-grade level — together with its colour-coded band (Very easy → Very difficult). It computes five grade-level formulas: Flesch–Kincaid Grade (0.39·words/sentence + 11.8·syllables/word − 15.59), Gunning Fog (0.4·[words/sentence + 100·(complex words ÷ words)], complex = 3+ syllables), SMOG (1.0430·√(polysyllables·30/sentences) + 3.1291), Coleman–Liau (0.0588·L − 0.296·S − 15.8, with L = letters per 100 words and S = sentences per 100 words) and the Automated Readability Index (4.71·characters/word + 0.5·words/sentence − 21.43). The five grade formulas are averaged into a single consensus grade level with a plain-language verdict such as “~8th grade — most adults can read this easily”. Alongside the scores it reports the full text statistics the formulas are built from — words, sentences, paragraphs, syllables, characters, complex (3+ syllable) words, average words per sentence and syllables per word, the longest and over-20-word sentences, and reading and speaking time — and lets the user copy a full text report.

Flesch Reading Ease shown on a 0–100 gauge with its band; 60–70 ≈ standard plain English (~8th–9th grade), the general web/SEO target
Five grade-level formulas: Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI, each with a grade interpretation
Averages the five grade formulas into a single consensus grade and a plain-language verdict
Reports full text stats: words, sentences, paragraphs, syllables, complex words, averages, longest sentence, reading & speaking time
Updates as you type and lets you copy a full text report; 100% in the browser

Methodology

How the Scores Are Computed In-Browser

All logic lives in a shared, pure module (textStatsEngine.ts) with no new dependency and no DOM access, so the same engine can power sibling tools (headline analyzer, keyword density / TF-IDF, content optimizer). Tokenization splits the text into words (letters and digits, keeping intra-word apostrophes and hyphens), sentences (on . ! ? with rough handling of common abbreviations, decimals and ellipses, and treating hard paragraph breaks as boundaries) and paragraphs (on blank lines). Syllables are estimated with a HEURISTIC counter: it counts contiguous vowel groups (treating y as a vowel), then applies corrections — silent trailing “e”, the “-le” ending, and common silent “-ed”/“-es” — with a floor of one syllable per word. A word with 3+ syllables counts as a complex / polysyllabic word for Gunning Fog and SMOG. The formulas use the verified coefficients above; every divisor is guarded so empty or degenerate input returns zeros rather than NaN or Infinity, and Flesch Reading Ease is clamped to 0–100 for display while the grade formulas are floored at 0. The five grade-level outputs are averaged into the consensus grade, which drives the verdict and the colour tone. Because Coleman–Liau and ARI use letters/characters per word rather than syllables, they cross-check the syllable-based formulas, and the consensus smooths out the disagreement that any single formula can show on short text. SMOG is noted as most reliable at 30+ sentences.

One pure, shared engine (textStatsEngine.ts) — no DOM, no new dependency — reusable by sibling SEO tools
Tokenizes words, sentences (abbreviation/decimal/ellipsis aware) and paragraphs; heuristic vowel-group syllable counter with silent-e / -le / -ed corrections
Uses the verified coefficients; complex word = 3+ syllables for Gunning Fog and SMOG
Guards every divisor (no NaN/Infinity); Flesch clamped 0–100, grade formulas floored at 0
Coleman–Liau and ARI use letters/characters (not syllables) and cross-check the syllable-based formulas; consensus = mean of the five grades

Limitations

Readability Scores Are Approximations — Not a Measure of Quality

The tool is deliberately honest about what readability formulas can and cannot do. They are approximations built almost entirely from two surface signals: average sentence length and average word length (syllables, letters or characters). That makes them fast and easy to compute, but it also means they do NOT measure actual comprehension, accuracy, tone, structure, flow, or whether the writing is good — you can earn an excellent score by chopping sentences in half while communicating nothing useful, and a dense but beautifully clear technical passage can score “difficult”. They are calibrated for English, so text in other languages produces misleading numbers, and the syllable count is a heuristic with no pronunciation dictionary, so unusual or non-English words can be off by a syllable. Different formulas can also disagree, especially on short text, which is why a consensus and the raw statistics are shown rather than a single verdict; SMOG in particular wants 30+ sentences. The honest guidance is to treat the score as a directional signal — a prompt to look for over-long sentences and needlessly complex words — and to write for the actual audience: for general web/SEO content aim around an 8th-grade level (Flesch 60–70), but technical, legal, medical and academic readers expect, and need, a higher level.

Formulas read only sentence length and word length — they do not measure comprehension, accuracy, tone, structure or quality
You can game any score by shortening sentences/words without improving meaning
Tuned for English; other languages give misleading scores; the syllable count is a heuristic, not exact
Formulas can disagree on short text — a consensus + the raw stats are shown instead of one number; SMOG wants 30+ sentences
Use as a guide and write for your audience: ~8th grade (Flesch 60–70) for general content, higher for technical/expert readers

Privacy & Security

Why Scoring Readability In-Browser Is a Privacy Win

Many online readability checkers send your text to a server to score it. Readability Score instead treats your text as a plain string that is tokenized and run through the formulas with ordinary JavaScript entirely on your device; nothing is fetched, uploaded, logged or stored, and no CDN is called for processing. That makes it safe to analyse unpublished drafts, confidential reports, client work or internal documents without exposing them. The result updates live as you type, the tool works offline once cached as a PWA, supports dark mode and a mobile layout with a sticky Sample / Copy report bar, has exactly three ad slots, includes a sample paragraph, and lets the user copy a full plain-text report of every score and statistic. The scoring logic is a small pure engine (textStatsEngine.ts) shared with sibling tools, with no new dependency — so the same trustworthy, local computation backs the whole readability/SEO family.

Text is tokenized and scored locally — never uploaded, no server, no CDN for processing
Safe for analysing unpublished drafts, confidential reports and internal documents
Updates live as you type; works offline once cached; dark mode and mobile with a sticky Sample / Copy bar; exactly three ad slots
Copy a full plain-text report of every score and statistic
Scoring is a small pure shared engine (textStatsEngine.ts) with no new dependency

Readability scoring: in-browser (AnyTool) vs typical online readability checkers
Capability	AnyTool	Typical online tools
Processing	Tokenizes + scores in your browser	Often sends your text to a server
Your text	Never uploaded, works offline	Uploaded / processed server-side
Drafts & confidential text	Safe — nothing leaves the browser	Text must be sent to be scored
Formulas	Flesch ease + FK, Fog, SMOG, Coleman–Liau, ARI + consensus	Often just Flesch / Flesch–Kincaid
Output	Gauge + per-formula grades + full stats + verdict	A score or two, sometimes paywalled
Honesty	States scores are approximations, English-only, not quality	Often implies the score grades your writing
Cost	Free, no sign-up, no limits	Free tier often limited / upsold

AnyTool is a 100% client-side readability scorer: paste any English text and it computes the six classic formulas in your browser — Flesch Reading Ease on a 0–100 gauge plus the Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI grade levels — averages the five grade formulas into a consensus US grade, reports the full text statistics (words, sentences, paragraphs, syllables, complex words, averages, longest sentence, reading & speaking time) and gives a plain-language verdict, with a copyable report. Honest caveat: readability formulas are approximations based on word + sentence length + a heuristic syllable count; they do not measure comprehension, accuracy, tone or whether the writing is good, they are tuned for English (other languages mislead), and the syllable count is heuristic — use them as a rough guide and write for your audience (≈8th grade / Flesch 60–70 for general web/SEO content, higher for technical readers). Comparison as of June 2026.

Cite This Page

Title: Readability Score (paste any English text and compute the six classic readability formulas in your browser — Flesch Reading Ease on a 0–100 gauge plus the Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI grade levels — with a consensus US grade level, full text statistics and a plain-language verdict; 100% client-side, nothing uploaded)
Author: AnyTool
Published: January 1, 2026
Modified: February 8, 2026
Section: SEO & Web
URL: https://www.anytool.tech/readability-score

Formatted Citation

AnyTool. "Readability Score (paste any English text and compute the six classic readability formulas in your browser — Flesch Reading Ease on a 0–100 gauge plus the Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau and ARI grade levels — with a consensus US grade level, full text statistics and a plain-language verdict; 100% client-side, nothing uploaded)." AnyTool, January 1, 2026. https://www.anytool.tech/readability-score

A privacy-first, 100% client-side Readability Score tool that estimates how hard a piece of English text is to read. The user pastes any text and, as they type, the tool computes the six classic readability formulas and the underlying text statistics entirely in the browser via a shared pure engine (textStatsEngine.ts) with no new dependency and no DOM access. It shows the Flesch Reading Ease on a 0–100 gauge — 206.835 − 1.015·(words/sentences) − 84.6·(syllables/words), higher = easier, with 60–70 the “standard” plain-English band around an 8th- to 9th-grade level (the general web/SEO target) — together with its colour-coded band from Very easy to Very difficult, and computes five grade-level formulas: 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 = 3+ syllables; SMOG = 1.0430·√(polysyllables · 30/sentences) + 3.1291; Coleman–Liau = 0.0588·L − 0.296·S − 15.8 with L = letters per 100 words and S = sentences per 100 words; and ARI = 4.71·(characters/words) + 0.5·(words/sentences) − 21.43. The five grade formulas are averaged into a single consensus grade with a plain-language verdict (e.g. “~8th grade — most adults can read this easily”). Tokenization splits the text into words (letters/digits, keeping intra-word apostrophes and hyphens), sentences (on . ! ? with rough abbreviation, decimal and ellipsis handling and treating hard paragraph breaks as boundaries) and paragraphs (blank lines); syllables are estimated with a heuristic vowel-group counter (y as a vowel) with silent-e, -le and common -ed/-es corrections and a one-syllable floor. Every divisor is guarded so empty input returns zeros rather than NaN/Infinity, Flesch is clamped to 0–100 and the grade formulas floored at 0. Alongside the scores it reports the full text statistics the formulas are built from — words, sentences, paragraphs, syllables, characters, complex (3+ syllable) words, average words per sentence and syllables per word, the longest and over-20-word sentences, and reading and speaking time — and lets the user copy a full plain-text report. The tool is deliberately HONEST: readability formulas are approximations built almost entirely from sentence length and word length, so they do NOT measure comprehension, accuracy, tone, structure or whether the writing is good (you can game any score by chopping sentences while saying nothing), they are calibrated for English so other languages mislead, the syllable count is a heuristic with no pronunciation dictionary, and formulas can disagree on short text (SMOG wants 30+ sentences) — so a consensus and the raw stats are shown rather than a single verdict, and users are told to treat the score as a directional guide and write for their audience (≈8th grade / Flesch 60–70 for general web/SEO content, higher for technical, legal, medical or academic readers). It is 100% client-side: the text is tokenized and scored on the user’s device, nothing is fetched, uploaded, logged or stored, and no CDN is called for processing, which makes it safe for unpublished drafts and confidential documents; it updates live as you type, works offline once cached, supports dark mode and mobile with a sticky Sample / Copy report bar, has exactly three ad slots, includes a sample paragraph, and the shared scoring engine also powers sibling tools (headline analyzer, keyword density / TF-IDF, content optimizer).

How do I check the readability score and grade level of my writing &mdash; the Flesch Reading Ease, Flesch&ndash;Kincaid, Gunning Fog, SMOG, Coleman&ndash;Liau and ARI &mdash; without uploading my text?