About

Readability is not just a stylistic choice; it is a conversion metric. In high-stakes industries like finance, law, and healthcare, clarity reduces liability and support costs. For SEO, Google's NLP algorithms prioritize content that directly answers user queries without cognitive friction.

This tool goes beyond basic scoring by implementing a multi-algorithm approach. While the Flesch-Kincaid formula is standard for general web copy, the SMOG Index is the gold standard for healthcare compliance, and the Coleman-Liau Index is preferred for automated scraping as it relies on character count rather than syllable estimation. The integrated Visual Heatmap isolates difficult sentences, adverbs, and passive voice, allowing editors to surgically remove complexity.

Formulas

The SMOG Index is widely considered the most accurate for validating complex texts. It focuses on the density of polysyllabic words.

SMOG = 1.0430 √poly × 30sentences + 3.1291

The Coleman-Liau Index relies on character analysis rather than syllable counting, making it robust against non-standard vocabulary.

CLI = 0.0588L − 0.296S − 15.8

Where L is the average number of letters per 100 words, and S is the average number of sentences per 100 words.

Reference Data

Algorithm	Best Use Case	Target Score (General)	Formula Dependency
Flesch-Kincaid Reading Ease	Standard Web Copy, Blogs, Marketing	60 − 70	Syllables & Sentence Length
Flesch-Kincaid Grade	Education, Government Documents	8.0 − 9.0	Syllables & Sentence Length
Gunning Fog Index	Business Reports, Technical Manuals	8 − 10	Complex Words (3+ syllables)
SMOG Index	Healthcare, Legal Disclaimers	8 − 10	Polysyllables (3+) in 30 sentences
Coleman-Liau	Automated Assessment, OCR Text	8 − 10	Characters & Sentence Length
ARI (Automated Readability)	Technical Writing	8 − 10	Characters & Words

Frequently Asked Questions

Each algorithm weights variables differently. Flesch-Kincaid penalizes long sentences heavily, while Gunning Fog focuses on "complex words" (3+ syllables). A text with short sentences but very technical vocabulary might score "Easy" on Flesch but "Hard" on Fog. Use SMOG for strict compliance and Flesch for general engagement.

Yellow sentences are considered "Hard to Read" (typically >20 words). Red sentences are "Very Hard" (>25 words). Purple highlights indicate adverbs (which often weaken prose), and Blue highlights indicate passive voice constructions.

Citations often inflate sentence length and complexity scores artificially. It is recommended to remove bibliographies and extensive footnotes before analysis to get an accurate score of the prose itself.

The engine uses a heuristic approach based on vowel groupings and suffix exceptions. It has an accuracy of approximately 95-98% for standard English. It accounts for silent "e", "es", and common diphthongs.

Passive voice ('The ball was dropped by him') is grammatically correct but cognitively heavier than active voice ('He dropped the ball'). In technical writing, active voice reduces ambiguity about who performs the action.