Readability Score Calculator — Flesch Reading Ease & Grade Level

Analyze text instantly. Private by design—everything runs locally in your browser.

Text & Actions

0 words · 0 sentences · 0 syllables

Tip: Press Ctrl/Cmd + K to focus the text box. Ctrl/Cmd + Enter re-analyzes.

Results

Flesch Reading Ease:
Flesch–Kincaid Grade:
Automated Readability Index (ARI):
Gunning Fog Index:
SMOG Index:
Coleman–Liau Index:
Word Count:
Sentence Count:
Syllable Count:
Avg Words / Sentence:
Avg Syllables / Word:

Understanding Readability Scores

Readability scores are metrics designed to estimate the comprehensibility of a text. They typically consider factors like sentence length, word length, and the complexity of words (often based on syllable count).

Why are Readability Scores Important?

  • Audience Engagement: Helps ensure your content is accessible and engaging for your target audience.
  • SEO: Readability can indirectly influence SEO by improving user experience (longer dwell times, lower bounce rates).
  • Clarity: Encourages clear, concise writing.
  • Compliance: Certain industries or government documents may have specific readability requirements.
FormulaDescriptionScore Interpretation
Flesch Reading Ease 100-point scale: higher is easier. 90–100: Very easy (≈5th grade)
60–70: Plain English (≈8th–9th)
30–50: Difficult (college)
0–30: Very difficult (graduate)
Flesch–Kincaid Grade Level U.S. grade-level equivalent. Higher grades are harder; aim ≈8–10 for general web content.
Automated Readability Index (ARI) Grade estimate emphasizing characters/word. Similar to FK Grade Level.
Gunning Fog Index Years of education needed; focuses on ≥3-syllable words. Around 12 is high-school senior; aim <12.
SMOG Index Years of education; most accurate with ≥30 sentences. 10 ≈ 10 years of schooling.
Coleman–Liau Index Grade based on characters/word and sentences/100 words. Similar to FK Grade Level.

How This Tool Works

This Readability Score Calculator operates entirely client-side within your browser. No text data is sent to a server, ensuring your privacy. It analyzes your input by:

  • Counting words, sentences, and syllables.
  • Applying various mathematical formulas (Flesch-Kincaid, ARI, Gunning Fog, SMOG, Coleman-Liau) to these counts to generate the scores.
  • Providing detailed metrics to help you understand your text's complexity.

5 Fun Facts about Readability

Born to sell magazines

Rudolf Flesch created his score to make Reader’s Digest easier to read—clearer copy sold more subscriptions.

Origins

Grade isn’t grade

A “Grade Level 8” text isn’t written by 8th graders—it means ~8 years of schooling to read comfortably.

Metric nuance

Short ≠ simple

“Ion” is tiny but technical; “butterfly” is long yet easy. Formulas can’t see domain knowledge—just length.

Hidden complexity

Plain language laws

Governments push “plain language,” yet legal contracts still score Fog 18+—graduate-level reading.

Compliance gap

Structure boosts scores

Breaking sentences, using bullets, and swapping jargon for everyday words can raise Flesch by 10–20 points fast.

Quick wins

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