Readability Checker

How to use the Readability Checker

1. Paste your article, essay, email, report or landing-page copy into the box.
2. Click "Analyse readability". Everything is computed locally — nothing is uploaded.
3. Read the headline grade level: it is the average of the standard grade-based formulas.
4. Compare the six individual scores; they disagree slightly by design, because each weighs different signals.
5. Scroll to "Hard sentences" and rewrite the highlighted ones. Splitting one long sentence in two is usually the fastest win.

Why use ZillaKit's Readability Checker?

Readable writing gets read. Whether you are drafting a blog post that needs to rank, a university essay that needs to be clear, a product page that needs to convert, or public-health information that people have to be able to act on, the single biggest lever is sentence length and word complexity — and both are measurable. This tool runs six of the most widely used, peer-reviewed readability formulas at once: Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog Index, SMOG Index, Coleman-Liau Index and the Automated Readability Index. It counts syllables with a linguistic heuristic (vowel groups, silent-e handling, common suffix exceptions), identifies complex and polysyllabic words, and then flags the individual sentences dragging your score down so you know exactly what to rewrite. There is no word limit, no signup, no upload: the text stays in your browser tab, which matters if you are analysing unpublished, confidential or client work. Most professional writing aims for grade 8 to 10 — roughly the reading level of a popular newspaper. Legal and academic writing routinely lands at grade 16+, which is precisely why nobody reads it.

What the scores mean

Flesch Reading Ease runs from 0 to 100 (higher is easier): 90-100 is understandable by an 11-year-old, 60-70 is plain English, 30-50 is difficult, and below 30 is best described as academic. Flesch-Kincaid Grade Level, Gunning Fog, SMOG, Coleman-Liau and ARI all return a US school grade — grade 8 means the average 13-14 year old could follow it. Gunning Fog and SMOG focus on polysyllabic words, so jargon-heavy text scores worse there. Coleman-Liau and ARI count characters instead of syllables, so they punish long words rather than long-sounding ones. When the formulas disagree, trust the pattern rather than any single number: if five of six say grade 14, your text is hard regardless of which one you prefer.

FAQ

Is my text uploaded anywhere?

No. All counting, syllable analysis and scoring happens in JavaScript inside your browser tab. The page makes no network requests with your content, so it is safe for confidential drafts, client work and unpublished manuscripts.

What readability score should I aim for?

For general web content and marketing copy, aim for Flesch Reading Ease 60-70 and a grade level of 8-10. News writing sits around grade 9. Technical documentation for specialists can sit higher, but if you are writing for the public — health, government, finance — most guidelines ask for grade 8 or below.

How is the syllable count worked out?

English syllable counting has no perfect algorithm, so we use the standard heuristic: count groups of consecutive vowels, subtract silent trailing "e", handle "-le" endings, treat "y" as a vowel where appropriate, and apply exceptions for common suffixes such as "-ed", "-es" and "-ing". It is accurate for the overwhelming majority of English words, which is all the formulas require.

Why do the six formulas give different numbers?

They were calibrated on different corpora for different purposes — SMOG on health materials, Gunning Fog on business writing, ARI on military technical manuals. Each weighs sentence length and word difficulty differently. Treat them as six opinions, not six facts, and act on the consensus.

What counts as a "hard sentence"?

We flag sentences on the combination of length and word complexity. Roughly: over 20 words with several long words is "hard"; over 30 words, or very high syllable density, is "very hard". These are the sentences readers re-read or abandon, and splitting them is the single fastest way to improve every score at once.

Does it work for languages other than English?

The formulas are calibrated for English and the syllable heuristic is English-specific, so the scores are only meaningful for English text. The word, sentence and reading-time counts will still be roughly correct for other Latin-script languages.