Calculates Flesch Reading Ease, Flesch-Kincaid Grade Level, and Gunning Fog Index in real time. Know exactly what reading level your content targets.
Free · No SignupA readability score is a numerical measure of how easy a piece of text is to read and understand. Our readability score tool calculates three industry-standard formulas — the Flesch Reading Ease score, the Flesch-Kincaid Grade Level, and the Gunning Fog Index — giving you a comprehensive view of your content's accessibility from multiple angles.
Readability scoring was first developed in the mid-twentieth century for educational testing — to match textbooks to appropriate grade levels. Today it's used by content marketers, SEO specialists, UX writers, and bloggers to ensure their writing connects with their intended audience rather than talking over or under them.
The Flesch Reading Ease score, developed by Rudolf Flesch in 1948, is the most widely used readability formula in English-language content. It produces a score from 0 to 100, where higher numbers mean easier to read.
| Score Range | Reading Level | Best For |
|---|---|---|
| 90–100 | Very Easy | Children's books, simple instructions |
| 80–90 | Easy | Conversational content, simple blog posts |
| 70–80 | Fairly Easy | Consumer-facing content, news articles |
| 60–70 | Standard | Most blog posts, general-audience web content |
| 50–60 | Fairly Difficult | Professional and technical content |
| 30–50 | Difficult | Academic writing, specialist publications |
| 0–30 | Very Difficult | Legal, scientific, government documents |
The formula is: 206.835 − (1.015 × average sentence length) − (84.6 × average syllables per word). This means you have two levers to improve your score: shorten your sentences, or use simpler words. Shortening sentences is almost always the faster and more effective lever.
The Flesch-Kincaid Grade Level converts readability into a US school grade equivalent. A score of 8 means the text is readable by an 8th grader. A score of 12 means high school senior level. A score above 16 means the text requires college education to read comfortably.
For most online blog content, a target grade level of 6–8 is optimal. This isn't because your readers lack education — most blog readers are educated professionals — but because reading online is cognitively different from reading print. People read faster, scan more, and have shorter attention spans in a browser environment. A lower grade level accommodates this reading mode without talking down to anyone.
Hemingway famously wrote at a 4th-grade level. The most-shared news articles online average between Grade 6 and Grade 8. Top-performing marketing copy regularly scores Grade 5–7.
The Gunning Fog Index, developed by Robert Gunning in 1952, estimates the years of formal education required to understand a text on first reading. It weights two factors: average sentence length and the percentage of complex words (words with three or more syllables).
A Fog score of 12 means a high school graduate can read the text. A score of 17 or above typically means only university-educated specialists will find it comfortable. For blog content targeting a general audience, a Fog score under 12 is your target. For B2B technical content, under 14 is acceptable.
The Fog index is particularly useful for identifying jargon-heavy sections of your content — places where you've used five-syllable technical terms when two-syllable common words would do the same job.
Google doesn't publish a readability signal in its ranking documentation, but multiple studies and SEO experts have identified strong correlations between readability scores and search performance. Here's why the connection exists:
Yoast SEO, the most popular WordPress SEO plugin, includes readability scoring in its content analysis and gives green lights for Flesch scores above 60. This alone has established 60 as a widely accepted minimum threshold for SEO-focused blog content.
Average sentence length is the single biggest driver of readability scores. Moving from a 22-word average to a 15-word average can shift your Flesch score from "difficult" (50) to "standard" (65) without changing a single word's complexity. Use the Sentence Heatmap to identify and split your longest sentences.
Every time you use a 4-syllable word where a 2-syllable word would work, you drop your Flesch score. "Utilize" → "use." "Demonstrate" → "show." "Implement" → "build." "Facilitate" → "help." Go through your draft and ask: is there a shorter word that means the same thing?
Paragraph length doesn't appear in Flesch or Fog calculations, but it affects perceived readability on screen enormously. Keep paragraphs to 3–4 sentences maximum for web content. Two-sentence paragraphs are fine for emphasis.
Passive constructions add words and complexity. "The decision was made by the board" has more syllables and more words than "The board decided." Use the Passive Voice Checker to find and eliminate passive constructions throughout your draft.
The right target depends on your content type and audience:
Don't over-optimize. Content that scores 95 on Flesch may read as simplistic to a professional audience. The goal is matching your readability level to your specific readers, not chasing the highest possible score.
Benchmark: The average Flesch Reading Ease score of the top 10 Google results for most informational queries is between 55 and 65. If your content scores significantly below this range, it's likely contributing to higher bounce rates in your category.
For general blog content, aim for a Flesch Reading Ease score of 60–70. This range is labeled "Standard" and is appropriate for most adult general-audience content. Marketing and consumer-facing copy often targets 70–80 for maximum accessibility.
Not directly — Google doesn't use Flesch scores in its ranking algorithm. However, readability strongly influences dwell time, bounce rate, featured snippet eligibility, and voice search visibility, all of which do influence rankings indirectly.
Different tools may use slightly different implementations of the same formula, particularly in how they count syllables and detect sentence boundaries. Minor variations of 2–5 points are normal. The formula itself is standardized, but edge cases in syllable counting (contractions, hyphenated words, abbreviations) can produce differences.
Yes, but you'll need to work harder. Technical content requires some complex terminology. The key is to keep your sentence structure simple even when your vocabulary must be complex. Short sentences with technical words score much better than long sentences with those same words.
Both use the same two inputs (sentence length and syllables per word) but express the output differently. Flesch Reading Ease gives a 0–100 score where higher is easier. Flesch-Kincaid Grade Level gives a US school grade equivalent where lower is easier. For a blog post, Flesch 65 ≈ Grade 8.