Readability Score Calculator

Analyze Text with 6 Readability Formulas - Free & Instant

Check Your Text Readability

What Is a Readability Score?

A readability score estimates how difficult a passage of text is to understand. It combines two simple ideas: longer sentences are harder to follow, and longer words are harder to decode. The output is a US school grade level - a score of 8 means an 8th grader can read your text comfortably.

The 6 Readability Formulas

Flesch Reading Ease

Score 0-100. Higher = easier. 60-70 is standard for web content.

Flesch-Kincaid Grade Level

US grade level. Most web content should target Grade 8-10.

Gunning Fog Index

Years of education needed. Penalizes complex words and long sentences.

SMOG Index

Healthcare standard. Uses complex word density. Best for accuracy.

Coleman-Liau Index

Uses characters per word instead of syllables. Good for digital content.

Automated Readability Index (ARI)

Uses characters per word. Designed for technical documentation.

Target Audience Guide

  • Grade 5-6: General public, social media
  • Grade 7-9: Web content, blogs, marketing
  • Grade 10-12: Academic, technical writing
  • College+: Research papers, legal documents

Why Use This Over AI?

AI chatbots (ChatGPT, Claude, Gemini) cannot compute exact readability scores. They approximate based on pattern matching, often off by 2-3 grade levels. This tool uses the same deterministic formulas used by professional writers, editors, and publishers worldwide - every calculation is precise and reproducible.

Frequently Asked Questions

What is the best readability formula?

There is no single "best" formula - each has strengths. Flesch-Kincaid is most common for web content. SMOG is most accurate for healthcare. The consensus average across all 6 formulas is most reliable.

What grade level should web content target?

Aim for Grade 8-9 (Flesch Reading Ease 60-70) for general web audiences. This matches the average American reading level.

Is my text sent to a server?

No. All analysis runs entirely in your browser. Your text never leaves your device. 100% private.

How many words do I need?

At least 30 words and 3 sentences for meaningful results. 100+ words is recommended for accurate scores.

Can I use this for SEO?

Yes. Search engines favor content that matches the reading level of the target audience. Most web content should score between Grade 8-10.

What makes a sentence "hard to read"?

Sentences with more than 25 words, complex words (3+ syllables), or both are flagged as hard. Long sentences create cognitive load for readers.

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