Readability Analyzer

What Is Text Readability?

Readability measures how easy a piece of writing is to understand. It is quantified using formulas that analyse sentence length, word length (by syllable count or character count), and the proportion of complex words. High readability means readers can extract information quickly and accurately; low readability means they must work harder, reread, and are more likely to abandon the text.

The 5 Readability Formulas Explained

Flesch Reading Ease (0–100): The most widely used readability test. Scores above 70 are easy (plain English, everyday prose). Scores 30–70 are average (standard office documents, journalism). Below 30 is difficult (academic, legal, technical). Most web content should target 60–70.

Flesch-Kincaid Grade Level: Converts the Flesch formula into a US school grade equivalent. A score of 8 means an 8th-grade student can understand the text. General public web content targets grade 6–8; academic papers are typically grade 12–16.

Gunning Fog Index: Developed by Robert Gunning in 1952, this formula counts "complex words" (3+ syllables, excluding proper nouns and compound words) and average sentence length. A score of 12 requires a high school graduate; 17+ requires university education. Business writing should target 10–12.

SMOG Grade: Simple Measure of Gobbledygook, developed by G. Harry McLaughlin in 1969. Counts polysyllabic words (3+ syllables) across 30 sentences. Widely used in health literacy research — the US National Institutes of Health recommends targeting SMOG grade 6 for patient health information.

Coleman-Liau Index: Unlike other formulas, this uses character counts rather than syllable counts, making it more reliable for automated analysis. Outputs a US grade level. Particularly good for texts with unusual syllabification.

Target Readability by Content Type