Benchmarks

Research-backed metrics for sentence length, comprehension rates, and reading levels

Use these research-backed metrics to create effective UX text that users can quickly read and understand.

Sentence length targets

By content type

Buttons/CTAs · length

2-4 words ideal, 6 word maximum

Examples:

• “Save changes” (2 words)
• “Delete account” (2 words)
• “Send invitation” (2 words)
• “Create new project” (3 words)

Titles · length

3-6 words, 40 characters maximum

Examples:

• “Account settings” (2 words, 16 chars)
• “Your library” (2 words, 12 chars)
• “Create new post” (3 words, 15 chars)
• “Team collaboration” (2 words, 18 chars)

Error messages · length

12-18 words (including solution)

Examples:

• “We couldn’t process your payment. Check your card details and try again.” (12 words)
• “Upload failed. File is too large. Choose a file under 10MB.” (13 words)

Instructions · length

20 words maximum, 14 ideal

Examples:

• “Enter your email to receive a link to reset your password.” (12 words)
• “Upload a photo to personalize your profile.” (7 words)

Body copy · length

15-20 words per sentence average

Varies by context, but maintain this average across paragraphs for optimal readability.

Notifications · length

10-15 words for title + body

Examples:

• Title: “Update required” (2 words)
• Body: “Install the latest version to continue.” (6 words)
• Total: 8 words

Comprehension rates by sentence length

These metrics are based on user research studies measuring how well users understand interface text on first read.

8 words or fewer: 100% comprehension

Users understand sentences of 8 words or fewer with near-perfect comprehension on first read.

Examples:

• “Save changes to update your profile.” (6 words)
• “Your password was reset successfully.” (5 words)
• “No results found. Try different keywords.” (6 words)

14 words or fewer: 90% comprehension

Users understand sentences of 14 words or fewer with 90% comprehension on first read.

Examples:

• “We couldn’t save your changes. Check your connection and try again.” (11 words)
• “Enable notifications to get updates when your team mentions you.” (10 words)

25 words: Maximum before significant drop

Beyond 25 words, comprehension drops significantly. Users need to re-read or abandon the text.

If your sentence exceeds 25 words, break it into multiple sentences or use bullet points.

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Character and line length

Optimal ranges for readability

Line length

40-60 characters for maximum readability

This is the optimal range for reading speed and comprehension. Lines that are too long cause users to lose their place; lines that are too short cause excessive back-and-forth eye movement.

Button labels

15-25 characters

Short enough to scan quickly but long enough to be descriptive.

Examples:

• “Save” (4 chars)
• “Delete account” (14 chars)
• “Send invitation” (15 chars)

Page titles

30-50 characters

Provides context without overwhelming users.

Examples:

• “Account settings” (16 chars)
• “Privacy and security” (20 chars)
• “Billing and subscription” (24 chars)

Notification titles

35-45 characters

Visible in notification panels without truncation on most devices.

Examples:

• “New message from Sarah” (22 chars)
• “Your report is ready” (20 chars)

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Reading level guidelines

By audience

Target reading levels based on your audience ensures your content is accessible and easy to understand.

General public

7th-8th grade (Flesch-Kincaid)

Most consumer-facing products should target this level. It ensures accessibility for the widest audience.

Characteristics:

• Short sentences (12-15 words average)
• Common, everyday words
• Active voice
• Simple sentence structures

Example: “Your payment failed. Check your card details and try again.”

Professional tools

9th-10th grade

Business software and professional tools can assume slightly higher literacy, but still prioritize clarity.

Characteristics:

• Sentences up to 18 words
• Industry terms when necessary
• Mix of simple and compound sentences

Example: “Your workspace settings have been updated. Team members will see these changes the next time they log in.”

Technical products

10th-11th grade

Developer tools and technical products can use more specialized vocabulary, but should still avoid unnecessary complexity.

Characteristics:

• Technical terminology when needed
• Sentences up to 20 words
• Assumes domain knowledge

Example: “Deployment failed during the build step. Check your build logs for errors and verify your dependencies.”

Specialized fields

11th-12th grade (only when necessary)

Medical, legal, or highly specialized software. Use this level only when simpler language would sacrifice accuracy.

Characteristics:

• Domain-specific terminology required
• Complex concepts
• Longer sentences when needed for precision

Example: “Patient consent must be documented prior to initiating treatment. Ensure all regulatory requirements are met before proceeding.”

Higher reading level ≠ better quality

Simpler writing is almost always more effective, even for educated audiences. Write at the lowest reading level that maintains accuracy.

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Testing tools

Use these tools to measure and improve your UX text:

Hemingway Editor

Highlights complex sentences, passive voice, and readability issues. Free web version available.

Readable.com

Provides multiple readability scores (Flesch-Kincaid, SMOG, Coleman-Liau). Paid tool with free trial.

Microsoft Word

Built-in Flesch-Kincaid scoring under File > Options > Proofing > Show readability statistics.

How to use readability scores

1. Write your content first

   Don’t try to hit a specific score while drafting. Write naturally, then test.

2. Check the score

   Run your text through a readability tool to get your baseline score.

3. Identify problem sentences

   Tools like Hemingway will highlight sentences that are too complex.

4. Simplify iteratively

   • Break long sentences into shorter ones
   • Replace complex words with simpler alternatives
   • Convert passive voice to active voice
   • Remove unnecessary words
5. Re-test

   Check your score again. Repeat until you hit your target reading level.

Target score by product type:

• Consumer apps: Flesch-Kincaid grade 7-8
• Business software: Flesch-Kincaid grade 9-10
• Technical tools: Flesch-Kincaid grade 10-11

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Quick reference

At-a-glance metrics

Content type	Word count	Character limit	Reading level
Button/CTA	2-4 words	15-25 chars	7th grade
Title	3-6 words	40 chars	7th grade
Error message	12-18 words	—	7th grade
Instruction	14-20 words	—	7th-8th grade
Body text	15-20 words/sentence	40-60 chars/line	7th-10th grade
Notification	10-15 words total	35-45 chars (title)	7th grade

Comprehension thresholds

Remember these three key numbers:

• 8 words = 100% comprehension
• 14 words = 90% comprehension
• 25 words = Maximum before drop-off