What Is the Dale-Chall Word List? How It Affects Readability

The Dale-Chall word list is a set of familiar English words used by the Dale-Chall readability formula. If a word is not on the list, the formula treats it as a “difficult” word.

That makes Dale-Chall different from formulas like Flesch-Kincaid. Flesch-Kincaid mostly reacts to sentence length and syllables. Dale-Chall also asks a vocabulary question: are these words likely to be familiar to a broad audience?

If you want to test a draft, use the Dale-Chall Readability Calculator. If you also want Flesch Reading Ease and Flesch-Kincaid Grade Level, run the text through the main Flesch-Kincaid calculator or the broader Readability Score Checker.

#The short answer

The Dale-Chall word list helps estimate readability by separating common words from less familiar words.

In practice:

• Words on the list are treated as familiar.
• Words not on the list are counted as difficult.
• The formula combines the percentage of difficult words with average sentence length.
• The result is converted into a grade-like readability score.

So a passage can have short sentences and still score as difficult if it uses too many uncommon terms.

#Why the word list matters

Many readability formulas use word length as a shortcut for word difficulty. That can be useful, but it is not always fair.

For example, “through” has one syllable but may not be easier for every reader than “banana.” “Education” has more syllables, but many readers know it well. Word length helps, but familiarity is a different signal.

Dale-Chall tries to capture that difference. It pays attention to whether the vocabulary itself is likely to slow readers down.

That is why the formula is useful for:

• school reading materials
• patient education pages
• public information pages
• nonprofit and government content
• plain-language rewrites
• any draft where unfamiliar vocabulary is the main risk

#A simple example

Compare these two sentences:

1. “The city will repair the road next week.”
2. “The municipality will initiate roadway remediation next week.”

Both sentences are short. The second one is harder because the vocabulary is less familiar. A syllable-based formula will notice some of that, but Dale-Chall is especially designed to flag the unfamiliar-word problem.

A practical rewrite would keep the specific meaning but use common words where possible:

The city will start road repairs next week.

That version is not childish. It is just easier to process.

#How the Dale-Chall formula uses difficult words

The New Dale-Chall formula uses two main inputs:

• average sentence length
• percentage of difficult words

The common version of the formula is:

 1Raw score = 0.1579 × difficult-word percentage + 0.0496 × average sentence length

Then an adjustment is added when difficult words make up more than 5% of the passage:

 1Adjusted score = raw score + 3.6365

That adjustment is important. It means a text with a heavy share of unfamiliar words can jump into a harder range quickly, even when sentence length is not extreme.

#What counts as a difficult word?

In Dale-Chall, a difficult word is usually a word that is not found on the familiar-word list.

But you should not treat that as a moral judgment on the word. “Difficult” does not mean bad, pretentious, or forbidden. It means the word may be less familiar to the average reader used for the formula’s benchmark.

That distinction matters because some unfamiliar words are necessary:

• Medical content may need terms like “hypertension” or “dosage.”
• Legal content may need terms like “liability” or “jurisdiction.”
• Technical documentation may need product-specific vocabulary.
• Academic writing may need field-specific language.

The goal is not to remove every difficult word. The goal is to notice where vocabulary may create avoidable friction.

#How to interpret a Dale-Chall score

Dale-Chall scores are often mapped to grade ranges. A lower score generally means easier reading.

A rough interpretation looks like this:

Use this as a guide, not a promise. A readability formula cannot know your audience’s exact background, motivation, or prior knowledge.

#When Dale-Chall is better than Flesch-Kincaid

Dale-Chall is especially helpful when vocabulary familiarity matters more than sentence mechanics.

Use Dale-Chall when you are asking:

• Are the words themselves likely to be familiar?
• Is this public-facing page using too much insider language?
• Would a reader understand the vocabulary without extra explanation?
• Do two drafts have similar sentence length but different word difficulty?

Use Flesch-Kincaid Grade Level when you need a familiar school-grade estimate based mainly on sentences and syllables. Use Flesch Reading Ease when you want a quick 0–100 ease score. Use Dale-Chall when the vocabulary list adds useful context.

Most teams get the best signal by checking more than one score instead of treating one formula as the final answer.

#How to improve a Dale-Chall score without dumbing down the text

Start with the difficult words, but do not automatically delete them.

A better editing process looks like this:

1. Keep necessary terms. If a word is accurate and important, keep it.
2. Replace unnecessary formal wording. “Commence” can often become “start.” “Utilize” can often become “use.”
3. Explain specialist terms once. If the term must stay, define it in plain language the first time it appears.
4. Shorten sentences around hard terms. Difficult vocabulary is easier to handle when the sentence structure is clean.
5. Retest after editing. A small number of clearer word choices can noticeably change the score.

The aim is not babyish writing. The aim is writing that respects the reader’s time.

#Common mistakes when using the word list

#Mistake 1: Treating the list as a banned-word list

The familiar-word list is a measurement tool, not a style guide. Some words outside the list are exactly the right words.

#Mistake 2: Ignoring audience knowledge

A word may be unfamiliar to a general audience but completely normal for your readers. For example, “cache” is common in software documentation but not always familiar in consumer health content.

#Mistake 3: Looking only at the final score

The score is useful, but the diagnosis matters more. If the score is high because of a few necessary terms, define those terms. If it is high because every sentence is loaded with formal vocabulary, rewrite more aggressively.

#Mistake 4: Comparing unrelated content types

A fourth-grade classroom handout, a legal notice, and a developer guide should not have the same target. Choose a score range that fits the job of the page.

#A practical editing checklist

Before publishing a public-facing page, ask:

• Are the most important terms familiar to the reader?
• Can any formal words become common words without losing accuracy?
• Are technical terms explained near where they appear?
• Are long sentences carrying too many unfamiliar words at once?
• Does the Dale-Chall score agree or disagree with Flesch-Kincaid, SMOG, or Gunning Fog?

If Dale-Chall is much harsher than the other scores, vocabulary is probably the issue. If all formulas are harsh, both sentence structure and word choice may need work.

#Bottom line

The Dale-Chall word list is useful because it checks something many formulas miss: word familiarity.

Use it when you care about plain language, public comprehension, educational materials, or vocabulary-sensitive content. Keep necessary terms, replace needless jargon, explain specialist language, and test the draft again.

For a quick check, use the Dale-Chall Readability Calculator. For a broader view, compare it with the main Flesch-Kincaid calculator and the Readability Score Checker.