What Is a Good Readability Score? The Complete Guide

You've written a blog post, a policy document, or a patient information leaflet. Before publishing, you check the readability score. It says 42. Is that good? Bad? Depends on what you're writing and who's reading it.

Readability scores measure how easy a piece of text is to read. They use mathematical formulas based on sentence length, word length, and syllable count to estimate the reading level required to understand the text. The score doesn't measure quality, accuracy, or persuasiveness — just how accessible the language is.

Understanding readability scores helps you calibrate your writing for your audience. A legal brief and a children's health leaflet serve different readers and need different reading levels.

The Major Readability Formulas

Flesch Reading Ease (FRE)

The most widely used readability formula. Scores range from 0 to 100, where higher = easier to read.

Formula: 206.835 − (1.015 × average sentence length) − (84.6 × average syllables per word)

Target for most content: 60-70. This is the range where content is accessible to the broadest audience without feeling dumbed down.

Flesch-Kincaid Grade Level

Uses the same inputs as Flesch Reading Ease but outputs a US school grade level instead of a 0-100 score.

Formula: (0.39 × average sentence length) + (11.8 × average syllables per word) − 15.59

Target for most content: Grade 7-9. Major newspapers write at grade 7-8. Government plain language guidelines typically target grade 6-8.

Gunning Fog Index

Estimates the years of formal education needed to understand the text on a first reading.

Formula: 0.4 × (average sentence length + percentage of complex words)

Complex words = words with 3+ syllables (excluding proper nouns, compound words, and common suffixes).

Target: 8-10 for general business content. The Wall Street Journal averages around 11.

SMOG Index

Simplified Measure of Gobbledygook. Designed specifically for healthcare content and considered more accurate for shorter texts.

Formula: 3 + √(number of polysyllabic words in 30 sentences)

SMOG is commonly used for patient education materials, where readability directly affects health outcomes. Target: grade 6-8 for patient-facing content.

Coleman-Liau Index

Unlike other formulas, Coleman-Liau uses character count rather than syllable count, making it easier to compute programmatically.

Formula: (0.0588 × average letters per 100 words) − (0.296 × average sentences per 100 words) − 15.8

Outputs a US grade level. Useful as a cross-check against Flesch-Kincaid.

Which Formula Should You Use?

For most purposes, Flesch Reading Ease + Flesch-Kincaid Grade Level give you a reliable picture. Use SMOG as an additional check for healthcare content.

Target Scores by Content Type

These are targets, not rules. A readability score of 45 is perfectly appropriate for a scientific paper but a problem for a patient information leaflet.

What Affects Readability

Sentence Length

The single biggest factor. Long sentences are harder to process because the reader must hold more information in working memory.

The fix: Vary sentence length. Mix short sentences (under 10 words) with medium sentences (15-20 words) and occasional longer sentences (25+ words). Monotonous sentence length — whether all short or all long — is harder to read than varied length.

Word Length and Syllable Count

Multi-syllable words increase reading difficulty. This doesn't mean you should avoid all long words — "implementation" is sometimes the right word. But if every sentence has three 4+ syllable words, readability drops.

The principle: Use the simplest word that conveys your meaning precisely. Don't simplify to the point of losing precision, but don't complicate for the sake of sounding formal.

Passive Voice

Passive voice ("The report was written by the team") is longer and harder to process than active voice ("The team wrote the report"). It also hides the actor, which can create ambiguity.

Passive voice isn't always wrong — it's appropriate when the action matters more than the actor, or in scientific writing conventions. But excessive passive voice reduces readability.

Jargon and Technical Terms

Industry jargon is readable to insiders but impenetrable to outsiders. If your audience includes non-specialists, define technical terms on first use or replace them with plain language equivalents.

Paragraph Length

Long paragraphs (200+ words) are visually dense and intimidating, especially on screens. Shorter paragraphs (50-150 words) with clear topic sentences improve scannability.

How to Improve Readability Without Dumbing Down Content

Improving readability doesn't mean simplifying your ideas. It means expressing complex ideas more clearly.

Strategy 1: Split Long Sentences

Before (38 words):

"The implementation of the new customer relationship management system, which was originally scheduled for completion in Q3 but was delayed due to vendor issues and integration challenges, is now expected to go live in early Q4."

After (two sentences, 14 + 18 words):

"The new CRM implementation was delayed by vendor issues and integration challenges. It's now expected to go live in early Q4, pushed back from the original Q3 target."

Same information, half the cognitive load.

Strategy 2: Replace Complex Words

Strategy 3: Use Active Voice

Strategy 4: Break Up Dense Paragraphs

If a paragraph exceeds 4-5 sentences, consider splitting it. Use subheadings to break long sections into scannable chunks.

Strategy 5: Use Lists for Multiple Items

Before:

"The report should include an executive summary, a description of the methodology, a presentation of the findings, an analysis of the results, a set of recommendations, and a list of references."

After: The report should include:

• Executive summary
• Methodology description
• Findings
• Analysis
• Recommendations
• References

Lists are easier to scan, easier to remember, and take up less cognitive processing.

When Low Readability Is Acceptable

Not all content should target a grade 7 reading level. Some contexts require — and their audiences expect — complex language:

Even in these contexts, readability can usually be improved at the margins: shorter sentences, fewer nominalisations, active voice where appropriate, and defined terms on first use.

Readability and Accessibility

Readability scores are particularly important for content that must be accessible to diverse audiences:

Government Content

Many countries have plain language requirements for government communications:

• Australia: Style Manual recommends clear, accessible language
• United States: Plain Writing Act (2010) requires federal agencies to use plain language
• United Kingdom: GOV.UK style guide targets a reading age of 9
• New Zealand: Plain Language Act (2022) requires government content to be clear
• Ireland: EU Web Accessibility Directive applies to all public sector content

Healthcare Content

Health literacy is a critical equity issue. Approximately 40-50% of adults in English-speaking countries have limited health literacy. Patient-facing content at grade 12+ reading level excludes a significant portion of the population.

Financial Content

Consumer financial content (loan documents, insurance policies, terms and conditions) that's too complex leads to poor decision-making and regulatory risk.

Limitations of Readability Scores

Readability scores are useful but imperfect. Understanding their limitations helps you use them appropriately:

Best practice: Use readability scores as one input, not the only input. Combine with human review for overall quality — structure, logic, engagement, accuracy, and audience appropriateness.

Checking Your Readability Score

You can check readability scores using free tools. A readability checker analyses your text and returns scores across multiple formulas, along with specific suggestions for improvement.

What to check:

• Flesch Reading Ease score (target 60-70 for general content)
• Flesch-Kincaid Grade Level (target 7-9 for general content)
• Average sentence length (target 15-20 words)
• Percentage of complex words (target under 15% for general content)
• Passive voice percentage (target under 15%)

Frequently Asked Questions

What readability score should I aim for?

Flesch Reading Ease of 60-70 for most content. Adjust based on your audience: higher (70-80) for consumer content, lower (40-50) for technical content. The key is matching the reading level to your audience, not hitting a universal number.

Is a higher readability score always better?

No. A Flesch Reading Ease of 90 is appropriate for children's content but would feel oversimplified for a business audience. Match the score to the audience and context.

Do readability scores affect SEO?

Not directly — Google doesn't use readability scores as a ranking factor. However, content that's easier to read tends to have lower bounce rates, higher engagement, and more sharing — all of which indirectly benefit SEO. Google's helpful content guidelines emphasise content that's useful and accessible.

Should I rewrite existing content to improve readability?

Prioritise content that's read by broad audiences (website content, marketing, policies, patient information). Technical content for specialist audiences may not need readability optimisation.

Can I improve readability without changing the meaning?

Almost always yes. Splitting long sentences, replacing unnecessarily complex words, using active voice, and adding structure (headings, lists) all improve readability without changing the substance.

What's the readability of famous texts?

Key Takeaways

• Readability scores measure how easy text is to read based on sentence length, word length, and syllable count. They don't measure quality, accuracy, or engagement.
• Target Flesch Reading Ease of 60-70 for most general content. Adjust for your specific audience.
• Sentence length is the biggest lever — aim for 15-20 words average, with variety.
• Use the simplest word that's precise enough — "use" instead of "utilise," "help" instead of "facilitate."
• Low readability is acceptable in specialist contexts (academic, legal, clinical) but can usually be improved at the margins.
• Readability scores have limitations — combine with human review for structure, logic, and engagement.
• Check your score with a readability checker before publishing.

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This article is for informational purposes. Readability targets vary by audience, industry, and regulatory requirements. Always consider your specific audience's needs and any applicable plain language legislation.