How to Improve Your Content's Readability Score

What Are Readability Formulas?

Readability formulas are mathematical algorithms that estimate reading difficulty based on measurable text properties — primarily sentence length and word complexity (syllable count or word length). They were originally developed for educational publishers in the mid-20th century to match books with appropriate grade levels. Today they are widely used by content marketers, SEO professionals, and UX writers to evaluate web content.

The most widely used readability formulas for web content:

• Flesch Reading Ease: Scores from 0 to 100. Higher is easier. Calculated from average sentence length and average syllables per word.
• Flesch-Kincaid Grade Level: Expresses reading difficulty as a US grade level. Grade 8 = accessible to most adults.
• Gunning Fog Index: Uses the percentage of complex words (3+ syllables) and average sentence length to estimate years of formal education needed.
• SMOG Grade: Based on polysyllabic word count. Popular in healthcare communications.
• Automated Readability Index (ARI): Uses character count per word rather than syllable count, making it computationally simpler.

Understanding the Flesch Reading Ease Scale

Flesch Reading Ease is the most commonly referenced score for web content:

Score	Difficulty	Best for
90–100	Very easy	Children's books
70–90	Easy	Consumer websites, news articles
60–70	Standard	Blog posts, marketing copy
50–60	Fairly difficult	Academic/professional content
30–50	Difficult	Academic journals
0–30	Very difficult	Legal/technical specialists

For most web content, aim for 60–70. This reaches the widest audience — including non-native speakers and mobile readers who skim rather than read deeply.

What Affects Readability

The two biggest factors are sentence length and word difficulty:

Sentence length: Long sentences force readers to hold more information in working memory. Each clause adds cognitive load. Short sentences are processed faster. Aim for an average of 15–20 words per sentence. Vary the length — monotonous short sentences feel choppy — but keep the average down.

Word complexity: Multi-syllabic words require more mental effort than simple ones. "Utilise" (3 syllables) is harder than "use" (1 syllable). "Commence" is harder than "start." "Necessitate" is harder than "need." Replace complex words with simpler synonyms wherever the meaning is preserved.

Other factors that affect readable feel (less captured by formulas):

• Paragraph length — 2-4 sentences per paragraph is ideal for web reading
• Use of headings and subheadings to guide scanners
• Bullet points and numbered lists for parallel items
• Active voice vs passive voice (active is clearer and more direct)
• Concrete language vs abstract language (specific examples beat vague concepts)

Reading Time and Why It Matters

Displaying a reading time estimate at the top of articles sets user expectations and reduces bounce rate — readers are more likely to stay if they know the content will take 5 minutes, not 20.

Average adult reading speed for web content: approximately 200–250 words per minute. A 1,000-word article takes about 4–5 minutes to read; a 2,000-word article takes about 8–10 minutes.

Our Reading Time Estimator calculates estimated reading time and Flesch readability score simultaneously. Paste your content and get instant feedback — useful for checking your blog posts before publishing.

Frequently Asked Questions

What is a good Flesch Reading Ease score?

60–70 is considered standard (easy to read, understood by 13-15 year olds). 70–80 is easy (plain English, suitable for most audiences). Below 30 is very difficult (academic/technical writing). Blog posts and marketing copy should aim for 60-70+. Web content should be even higher — 65 to 80 is ideal.

Does readability affect SEO?

Readability is not a direct Google ranking factor, but it affects metrics Google does measure: time on page, bounce rate, and user satisfaction signals. Content that is easier to read keeps users engaged longer. Google's NLP also understands natural language better than keyword-stuffed, unreadable text.

What is the average reading speed?

The average adult reading speed is approximately 200-250 words per minute for typical web content. Technical content is read more slowly (150-200 wpm) and simple content more quickly (300+ wpm). A 1,500-word article takes approximately 6-8 minutes to read.

How do I improve my content's readability score?

Use shorter sentences (aim for 15-20 words average). Use simpler words — 'use' instead of 'utilise', 'start' instead of 'commence'. Break long paragraphs into 2-3 sentences. Use bullet points and headings to break up blocks of text. Avoid jargon for non-specialist audiences.