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Flesch-Kincaid Readability Calculator

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Readability Score

About this Flesch-Kincaid calculator

The Flesch-Kincaid tests measure how hard a text is to read. The Reading Ease score runs from 0 to 100: higher means easier. The Grade Level converts the same numbers into a US school grade, so a score of 8.2 means “comfortable for an eighth grader”. Both scores are built from two simple ratios — words per sentence and syllables per word.

US federal agencies have aimed official documents at plain-language readability for decades, and style guides from AP to most content teams target a Reading Ease of 60–70. Marketing copy usually sits at 60–80, news around 50–60, academic papers much lower.

Paste any text — an essay, an email, a landing page — and get both scores instantly, together with word, sentence and syllable counts. Syllables are estimated by a standard heuristic, so scores match other readability checkers within about a point.

When the pasted text is mostly Cyrillic, the calculator switches to the modified Flesch formula used for Russian: 206.835 − 1.52 × (words ÷ sentences) − 65.14 × (syllables ÷ words). The US grade line is shown only for Latin-script texts, because its scale was calibrated on English.

Reading ease score bands

Score Level Typical for
90–100 Very easy Very easy — children's books, comics
70–89 Easy Easy — young adult fiction, plain summaries
60–69 Plain English Plain English — the general-audience target
50–59 Fairly difficult Fairly difficult — high school textbooks
30–49 Difficult Difficult — college writing, most news analysis
0–29 Very difficult Very difficult — legal documents, research papers

The formulas

Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). The two subtractions mean long sentences and long words both pull the score down.

Grade Level = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. It answers “which US school grade can read this comfortably?”. A grade of 8 means eighth grade (about age 13–14); 12 finishes high school, and values above 16 point at postgraduate reading.

Note the rough inverse relationship: a Reading Ease around 60–70 corresponds to a Grade Level of roughly 8–9.

RE = 206.835 − 1.015·(words/sentences) − 84.6·(syllables/words)

How to check readability

  1. Paste your text: Any length from a paragraph to a full article works.
  2. Read the scores: Reading ease, grade level and the raw counts appear instantly.
  3. Edit and re-check: Shorten sentences or swap long words, then watch the score improve.

FAQ

What is a good Flesch-Kincaid score?

For general web content, 60–70 Reading Ease is the classic target: plain English that most adults read comfortably. Anything above 70 is even friendlier.

What does the grade level number mean?

It maps to US education levels: 1–5 elementary, 6–8 middle school, 9–12 high school (the US has 12 school grades, not 11). Values above 12 keep going: 13–16 ≈ college, 17+ ≈ graduate study — so a score of 18 simply means postgraduate-level text, not an 18th school grade.

How accurate is the syllable count?

Syllables are estimated with the standard vowel-group heuristic used by readability tools. Scores typically land within about one point of manual counting.

Does it work for languages other than English?

Yes: Cyrillic vowels are counted for syllables, sentences are split correctly, and for mostly-Cyrillic text the calculator applies the modified Flesch formula adapted for Russian. The US grade level is still English-only, so it is hidden for Russian texts.

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