Dale-Chall Readability Calculator Calculate Dale-Chall readability score using familiar word analysis.

What Is Dale-Chall Readability?

The Dale-Chall Readability Score uses a list of ~3,000 words that 80% of 4th graders understand. Words not on this list are "difficult." Formula: 0.1579*(% difficult words) + 0.0496*(avg sentence length), plus 3.6365 if difficult words exceed 5%. This vocabulary-based approach catches complexity that sentence-length formulas miss. The score is validated against actual comprehension data, making it one of the most reliable readability measures.

Why Use Dale-Chall Readability?

• Identifies specific difficult words to replace
• Vocabulary-based analysis catches complexity others miss
• Validated against comprehension data
• Actionable word-level feedback
• Widely used in education and publishing

Common Use Cases

Textbook Publishing

Match materials to grade levels based on vocabulary.

Plain Language

Identify unfamiliar vocabulary in government documents.

ESL Content

Create materials with familiar vocabulary.

Technical Writing

Identify terms to define or replace.

Technical Guide

PDW = % difficult words, ASL = avg sentence length. Score = 0.1579*PDW + 0.0496*ASL + 3.6365 (if PDW > 5%). Score ranges: <=4.9 = grade 4, 5-5.9 = grades 5-6, 6-6.9 = grades 7-8, 7-7.9 = grades 9-10, 8-8.9 = grades 11-12, 9+ = college.

Tips & Best Practices

• 1
  The 5% difficult word threshold causes a significant score jump
• 2
  The difficult word list shows exactly what to simplify
• 3
  Aim for Dale-Chall below 6.0 for web content
• 4
  Combine with sentence-length formulas for best results

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Frequently Asked Questions

Q How many words on the familiar list?

About 3,000 words that 80% of 4th graders understand.

Q Why the score jump at 5%?

Adding 3.6365 reflects the sharp comprehension drop when more than 1 in 20 words is unfamiliar.

Q How does it compare to Flesch-Kincaid?

Dale-Chall uses word familiarity, FK uses syllables. Dale-Chall is often considered more reliable.

Q Are proper nouns difficult?

Proper nouns not on the list are counted as difficult.

Q Is the 1995 revision different?

Updated word list, same core formula.

About This Tool

Dale-Chall Readability is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.