Understanding Readability Scores & Optimizing Writing
Readability scores measure how easy your text is to understand. They are used by content marketers, technical writers, educators, healthcare communicators, and SEO specialists to ensure their writing matches their audience's reading level.
- Learn what Flesch-Kincaid, Gunning Fog, SMOG, and other readability scores mean.
- Covers 1. what readability scores measure.
- Covers 2. the six major formulas.
- Covers 3. how to improve your score.
1. What Readability Scores Measure
All readability formulas measure the same basic things: sentence length and word complexity. Longer sentences are harder to follow. Words with more syllables are harder to understand. The formulas weight these factors differently, which is why they give slightly different results.
Readability scores do not measure clarity of ideas, logical structure, or accuracy. A text can score well on readability while being poorly organized or factually wrong. Use scores as one input, not the only input.
2. The Six Major Formulas
Flesch Reading Ease
The most widely used readability formula. Scores range from 0 to 100, where higher means easier. The formula: 206.835 - 1.015 × (words/sentences) - 84.6 × (syllables/words). Aim for 60-70 for general web content.
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Converts the Flesch formula into a US school grade level. A score of 8.0 means an eighth grader can understand the text. Most newspapers write at grade 6-8.
Gunning Fog Index
Focuses on ‘complex words’ (three or more syllables). The formula: 0.4 × (words/sentences + 100 × complex words/words). Useful for business and technical writing.
Coleman-Liau Index
Uses character count instead of syllable count, making it faster to compute and more consistent. Developed for automated assessment of textbook readability.
SMOG Index
‘Simple Measure of Gobbledygook’ — specifically designed for healthcare materials. Focuses heavily on polysyllabic words. Often used to evaluate patient education materials.
Automated Readability Index (ARI)
Uses characters per word and words per sentence. No syllable counting needed, making it the fastest to compute. Often used in automated content analysis pipelines.
3. How to Improve Your Score
- Shorten sentences: Aim for 15-20 words per sentence. Break long sentences at natural pauses.
- Use simpler words: Replace ‘utilize’ with ‘use’, ‘subsequently’ with ‘then’, ‘commence’ with ‘start’.
- Use active voice: ‘The team completed the project’ is clearer than ‘The project was completed by the team.’
- Break up paragraphs: No paragraph should be more than 3-4 sentences on the web.
- Cut filler words: Remove ‘very’, ‘really’, ‘just’, ‘basically’, and ‘actually’ unless they add meaning.
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