Readability Score Checker
Measure reading difficulty with Flesch-Kincaid, Gunning Fog, and SMOG scores. Optimize your AI-generated content for your audience.
How to Use the Readability Score Checker
- Paste your text into the input area — results update automatically.
- Review the Flesch Reading Ease score: higher is easier (70+ is plain English).
- Check the Flesch-Kincaid Grade Level: the US school grade required to understand the text.
- Review the Gunning Fog Index: years of formal education needed to read comfortably.
- Follow the advice below the stats to improve readability for your target audience.
Key Features
- Three readability formulas — Flesch Reading Ease, Flesch-Kincaid Grade Level, and Gunning Fog Index.
- Audience level label — Easy, Standard, Fairly Difficult, Difficult, or Very Difficult.
- Actionable advice — specific suggestions based on your score.
- Real-time calculation — updates as you type.
- Essential for AI content — AI-generated text often scores too difficult; this tool helps you fix it.
Frequently Asked Questions
What is the Flesch Reading Ease score?
The Flesch Reading Ease score rates text on a scale from 0 to 100. Higher scores indicate easier reading. A score of 70–80 is considered easy and appropriate for most web content. Scores of 60–70 are standard and suitable for a general adult audience. Scores below 50 are considered difficult and typically require a college education to read comfortably. The formula penalizes long sentences and polysyllabic words, rewarding concise writing with common vocabulary.
What grade level should my content target?
For most web content and blog posts, a Flesch-Kincaid Grade Level of 7–9 (middle school) is ideal. This does not mean the content is unsophisticated — it means the language is clear and accessible. Harvard Business Review, Wikipedia, and most major newspapers target a grade 8–10 reading level. Technical documentation and academic papers appropriately target grade 12 and above. For AI-generated content specifically, models tend to produce formal, high-grade-level text that benefits from simplification.
Why does AI-generated content often score poorly on readability?
AI language models are trained on diverse text including academic papers, technical documentation, and formal writing. They tend to favor complex sentence structures, nominalization (turning verbs into nouns), passive voice, and polysyllabic vocabulary — all patterns that increase reading difficulty scores. Running AI-generated drafts through a readability checker and simplifying sentences over 25 words, replacing jargon with plain terms, and using active voice typically improves both readability scores and reader engagement.
What is the Gunning Fog Index?
The Gunning Fog Index estimates the years of formal education required to understand a piece of writing on first reading. A score of 8 is ideal for mass-market content. Most newspapers target a Fog Index of 10–12. Academic journals typically score 15–20. The formula counts the percentage of “complex words” (3+ syllables) and average sentence length. Unlike Flesch scores, a lower Gunning Fog score means easier reading.