Readability Checker

Check text readability — tune content to your audience's reading level

Writing that is too complex loses readers. Writing that is too simple fails to convey technical depth. Finding the right readability level for your audience — whether you are writing landing page copy, academic journal articles, employee training materials, legal notices, or blog posts — requires objective measurement. ToolJiffy Readability Checker computes six major readability scores from any text you paste, helping you calibrate your writing for your target audience, entirely in your browser.

Six readability formulas explained

• Flesch Reading Ease (0–100): Higher scores = easier reading. Developed by Rudolf Flesch in 1948. Formula: 206.835 − 1.015×(words/sentences) − 84.6×(syllables/words). Targets: 60–70 for general public, 30–50 for academic text.
• Flesch-Kincaid Grade Level: Maps to US school grade levels. A score of 8 means an 8th-grader should be able to read the text. Targets: Grade 6–8 for accessible web content, Grade 12+ for academic writing.
• Gunning Fog Index: Estimates years of education needed to understand text on the first reading. Uses the percentage of "complex words" (3+ syllables). Business communication targets under 12.
• SMOG Index: Designed for health communication — predicts the education level required to understand healthcare materials. Validated against patient comprehension studies.
• Coleman-Liau Index: Based on characters per word rather than syllables, making it more language-neutral and consistent for computer processing.
• Automated Readability Index (ARI): Also character-based. Used extensively in US military documentation standards and technical writing guidelines.

How to improve your readability score

• Shorten sentences: Aim for an average of 15–20 words per sentence. Long complex sentences with multiple clauses dramatically increase grade level scores.
• Use shorter words: Prefer "use" over "utilize," "help" over "facilitate," "show" over "demonstrate." Each polysyllabic word raises the Gunning Fog and SMOG scores.
• Active voice: "The system processes requests" scores better than "Requests are processed by the system" — fewer words, same meaning.
• Break long paragraphs: Shorter visual blocks improve perceived readability even without changing grade-level scores.

Browser-native syllable counting algorithm

ToolJiffy uses a JavaScript implementation of the standard English syllable estimation algorithm: vowel-cluster counting with rule-based corrections for silent-e endings, common suffixes (-tion, -sion, -le), and word-final vowel rules. Sentence boundaries are detected using punctuation end-markers (., !, ?) with context to avoid triggering on abbreviations and decimals. All computation runs synchronously in your browser.

Step-by-step guide to checking readability

1. Paste your text: Copy your article, document, or email draft into the text area above.
2. Review scores: Examine the six readability scores alongside average sentence length, word count, and syllable statistics.
3. Revise and re-check: Edit your text to reduce long sentences and complex words, then re-run to verify improved scores.

Frequently asked questions

What readability scores does ToolJiffy calculate?

Calculates Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog Index, SMOG Index, Coleman-Liau Index, and Automated Readability Index (ARI).

What does the Flesch Reading Ease score mean?

Scores range 0–100. Higher = easier. Scores of 60–70 indicate standard accessible prose. Academic papers often score 30–50.

How does the Readability Checker work in browser memory?

ToolJiffy counts syllables using a JavaScript syllable algorithm, counts sentences by punctuation markers, and computes all formula values — 100% locally with no server uploads.

Is my text data uploaded to any cloud server?

No. All computation runs 100% locally in your browser. Your text never leaves your device.

What Flesch-Kincaid grade level should blog content target?

Most successful blog content targets Grade 6–8 (US middle school level), making it accessible to the widest possible adult audience.

What writing changes improve readability scores?

Shorten sentences (target under 20 words), use shorter words, prefer active voice, break long paragraphs, and replace jargon with plain-language equivalents.

Does the readability checker handle non-English text?

Readability formulas are calibrated for English. Results for non-English content should be interpreted cautiously as syllable and word length patterns differ.

Is ToolJiffy Readability Checker free without limits?

Yes. ToolJiffy is 100% free with unlimited text analysis, zero account registration, and zero server uploads.

Related text analysis tools

Count words with Word Counter, analyze word frequency with Word Frequency Counter, view full text statistics with Text Statistics, or count sentences with Sentence Counter.