Readability Analyzer
Score text with Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog, SMOG, and ARI. Get detailed stats on sentences, words, and syllables.
Flesch score
Very Difficult
~Post-Graduate
Avg grade level: 18.3
Flesch-Kincaid
17.4
Post-Graduate
Gunning Fog
21.2
Post-Graduate
SMOG Index
16.2
Post-Graduate
ARI
18.4
Post-Graduate
Sentences
5
Words
65
Characters
460
Syllables
154
Avg sent. length
13.0 words
Avg word length
7.1 chars
Syllables/word
2.37
Complex words
26 (40%)
Flesch Reading Ease scale
Free online readability checker with Flesch score, grade level, and five readability formulas
Writing clearly for your audience is as important as writing accurately. The Readability Analyzer on AlteredIdea scores your text against five established readability formulas: Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog Index, SMOG Index, and Automated Readability Index: giving you a comprehensive picture of how accessible your writing is. All analysis runs locally in your browser with no server calls.
Content writers, educators, healthcare communicators, and UX writers use readability scores to verify that their content matches the reading level of their audience. Targeting the right readability level reduces bounce rates, improves comprehension, and: for health, legal, and government content: meets compliance standards that require plain-language writing. The tool also includes detailed text statistics including syllable counts, average sentence length, and the percentage of complex words.
Step-by-step guide
- 1Paste your text
Copy any article, blog post, email, or document and paste it into the Text to Analyze panel. The analyzer works on any length of English text. - 2View the Flesch Reading Ease score
The large number at the top of the results panel is your Flesch Reading Ease score (0-100). Higher is easier. A score of 60-70 is considered standard, suitable for most general audiences. - 3Check the grade level breakdown
Four grade-level metrics: Flesch-Kincaid, Gunning Fog, SMOG, and ARI: each estimate the US school grade needed to comfortably read your text. The average gives a consensus grade level. - 4Review text statistics
The Statistics panel shows sentence count, word count, character count, syllable count, average sentence length, average word length, and percentage of complex words. - 5Copy the report
Click Copy report to save all scores and statistics to your clipboard in plain text format, ready to paste into a document or share with a collaborator.
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Frequently Asked Questions
- What is the Flesch Reading Ease score?
- The Flesch Reading Ease score (0-100) measures how easy a text is to read. Scores of 90-100 are very easy (5th grade level), 60-70 is standard (8th-9th grade), and scores below 30 are considered very difficult (professional/academic). Most general-audience content targets 60-70.
- What is the Flesch-Kincaid Grade Level?
- The Flesch-Kincaid Grade Level converts the Flesch formula into a US school grade number. A score of 8.0 means the text is appropriate for an 8th grader. Journalists typically target grade 8-10, while academic papers often score 12-16.
- What is the Gunning Fog Index?
- The Gunning Fog Index estimates the years of formal education needed to understand the text on a first reading. It emphasizes the percentage of complex words (3+ syllables). A score of 12 corresponds to a high school senior level.
- What is the SMOG Index?
- SMOG (Simple Measure of Gobbledygook) predicts the years of education needed to understand a text. It is considered the most accurate readability formula for health-related materials. It requires at least 30 sentences to produce a reliable score.
- What is the Automated Readability Index (ARI)?
- The ARI uses average word length (in characters) and average sentence length to estimate grade level. It is one of the faster formulas to compute and correlates well with other readability measures for most text types.
- What readability score should I target?
- For general web content and marketing copy, aim for a Flesch score of 60-70 (grade 8-9). For email newsletters, 70-80 works well. Technical documentation may legitimately score lower. Academic writing typically scores 30-50.
- Does readability affect SEO?
- Yes. Google's quality guidelines favor content that is clear and easy to understand for its intended audience. Overly complex text increases bounce rates, which is a negative engagement signal. Targeting appropriate readability for your audience improves both user experience and search rankings.
- What counts as a complex word?
- A complex word is any word with 3 or more syllables. Both the Gunning Fog and SMOG formulas use the percentage of complex (polysyllabic) words as a key factor in their grade-level calculations.
- Can I analyze AI-generated content?
- Yes. AI-generated text often scores as highly complex because models tend toward longer sentences and formal vocabulary. Pasting AI output into the analyzer helps you identify passages to simplify before publishing.
- Why do the four grade-level scores differ?
- Each formula weights different text features. Flesch-Kincaid and ARI emphasize sentence length, while Gunning Fog and SMOG focus on complex word counts. The average of all four gives the most balanced estimate of overall grade level.
AlteredIdea vs alternatives
vs ChatGPT / LLM APIs: LLMs give qualitative feedback on writing style but don't compute standardized readability scores. AlteredIdea gives precise, reproducible Flesch and grade-level numbers.
vs browser extensions: No install, no permissions, works on any device.
vs paid tools: Completely free, no account required.