Readability Checker

Readability score

All formulas

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This readability checker scores your writing the moment you paste it. You get a Flesch Reading Ease score on a 0–100 gauge with a plain-English reading level, plus the Flesch-Kincaid grade, Gunning Fog, SMOG, Coleman-Liau and Automated Readability Index in one table. It also shows average sentence length, syllables per word and the share of complex words, and flags long sentences so you know exactly what to fix. Use it to make web content, emails and reports easier to read.

What a Readability Score Tells You

A readability score estimates how easy a piece of text is to read and understand. Readability formulas look at measurable features of writing, mainly sentence length and word length, and turn them into a number.

The logic is simple. Long sentences make readers hold more in their heads before reaching the point. Long words with many syllables tend to be less common and harder to process. Text with short sentences and familiar words is usually easier to read, for everyone.

Scores come in two forms. Some give a 0–100 scale where higher means easier, like Flesch Reading Ease. Others give a grade level, roughly the years of US schooling needed to understand the text on first reading. A grade of 8 means an average 13- to 14-year-old should follow it.

What a score can’t tell you is whether your writing is accurate, well organized, persuasive or right for your audience. It measures text complexity, not comprehension or content quality. Use it as a quick, objective check alongside your own judgment.

Readability Formulas Behind the Scores

Each formula uses a slightly different recipe. Some count syllables, some count letters, and some focus on complex words. Because they weigh things differently, they rarely agree exactly. That is why this checker shows all six side by side: if most point to a similar grade, you can trust the overall picture.

Flesch Reading Ease and Flesch-Kincaid Grade Level

Flesch Reading Ease is the best-known readability test. It uses average words per sentence and average syllables per word:

206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)

Scores run from about 0 to 100. The checker labels them from “Very easy” (90+, around 5th grade) through “Standard” (60–69, 8th–9th grade) to “Very difficult” (below 30, college graduate). Most web content should aim for 60 or higher.

Flesch-Kincaid Grade Level uses the same two inputs but outputs a US school grade:

0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59

It is built into Microsoft Word and many other editors, so it is useful for comparing results across tools.

Gunning Fog, SMOG and Coleman-Liau

Gunning Fog Index focuses on complex words, counted here as words with three or more syllables. It estimates the years of formal education needed to understand the text. Business and technical writing often scores high.

SMOG Index also counts words of three or more syllables and gives a grade level. It is widely used for health and medical writing. It works best on longer texts, ideally 30 sentences or more, as the results table notes.

Coleman-Liau Index counts letters per word instead of syllables, plus sentences per 100 words. Automated Readability Index also uses characters per word. Letter-based formulas are less affected by how syllables are counted, which makes them a useful cross-check.

How to Test Your Text in Three Steps

  1. Paste your content. Add at least a few sentences of plain text into the box. For a web page, paste the main body copy, leaving out menus, buttons and footers. Headings and bullet lists without ending punctuation may be read as part of the next sentence, so paste body paragraphs for the cleanest result.
  2. Read the score. The gauge shows Flesch Reading Ease with its label and reading level. Green means 60 or above, amber 50–59, and red below 50. Below it, check the Flesch-Kincaid grade, word and sentence counts, average words per sentence, average syllables per word and complex words with their percentage. The table lists all six formulas and what each score means.
  3. Fix the flags. Tips appear when the average sentence runs over 20 words, when more than 15% of words are complex, or when sentences exceed 25 words. Edit your text in place; the scores update live. Use Clear to start over.

The checker runs 100% in your browser, so drafts and confidential documents are never uploaded.

Choosing a Target Grade Level for Your Audience

The right score depends on who is reading. Some rough guides:

  • General web content, blog posts, product pages: Flesch Reading Ease 60–70, around grade 7–9. Most adults read online text quickly and skim, so plain language works best.
  • Public information, health and government content: grade 6–8. Plain-language guidelines often recommend this range so information reaches as many people as possible.
  • Business and B2B content: grade 9–11 is common, but simpler still reads faster.
  • Academic, legal and medical writing: higher scores are normal because of technical terms, but clarity still matters.
  • Students and young readers: match the grade level to the class.

Writing at a lower grade level doesn’t mean writing down to people. Experts also prefer clear writing, especially on a phone. Aim for the simplest version that keeps your meaning precise, and keep the technical terms your audience expects.

Readability and SEO Performance

Readability is not a direct Google ranking factor. Google doesn’t run Flesch scores on your pages, and plugins like Yoast that show readability scores are writing aids, not ranking checks.

Readability still affects SEO indirectly. Google’s guidance asks for helpful, people-first content, and content that is easy to read is more likely to be understood, trusted and shared. Clear writing also helps:

  • Scannability. Short sentences and paragraphs suit how people read on screens.
  • Engagement. Readers who understand quickly are more likely to stay and act.
  • Answer extraction. Direct, simple sentences are easy for search engines and AI answer engines to quote as featured answers.
  • Accessibility. Simpler text helps readers with lower literacy, non-native speakers and people with cognitive disabilities.

Ways to Improve a Low Score

Start with the flags in the tips list, then edit section by section. Fixing the longest sentences usually moves the score most, because sentence length has a big effect on every formula. Recheck after each pass and stop once the text reads well; there is no need to push the score to its maximum.

Shortening long sentences

Find sentences over 25 words and split them. Look for “and”, “but”, “which” and “because” as natural break points. One idea per sentence is a good rule.

Mix lengths so the text doesn’t sound choppy. A few longer sentences are fine if most are short. Turn long lists inside sentences into bullet points.

Replacing complex words and passive voice

Swap long words for common ones where meaning allows: “use” for “utilize”, “help” for “facilitate”, “start” for “commence”. Keep technical terms your readers need, but explain them once.

Passive voice (“the report was written by the team”) is usually longer and less direct than active voice (“the team wrote the report”). This checker doesn’t flag passive voice, so look for it yourself, or use an editor like Hemingway Editor or Grammarly that highlights it.

Mistakes When Chasing a Perfect Score

  • Cutting sentences into fragments. Very short, choppy sentences score well but read badly.
  • Removing necessary terms. Replacing “mortgage” with a vague phrase to drop a syllable makes text less precise.
  • Oversimplifying for an expert audience. Developers, doctors and lawyers expect certain vocabulary.
  • Scoring tiny samples. A few sentences produce unstable results. Test full sections.
  • Ignoring structure. A good score can’t fix a confusing order, missing headings or walls of text.
  • Treating one formula as the truth. Compare several scores.
  • Writing for the tool. The goal is a reader who understands, not a green gauge.

Where Formulas Fail

Readability formulas count, they don’t understand. A sentence of short words can still be confusing, and a long word like “everybody” isn’t hard to read.

They are built for English prose, so results for other languages, code, lists, tables, bullet-heavy pages and poetry are unreliable. Syllable counts are estimates, and abbreviations or numbers can skew sentence counts. Read your text aloud or ask someone from your audience; it is the best test of all.

Writing Clearly for Real Readers

Use the score to find hard spots, then edit for the person reading. Track length with the Word Counter, check repetition with the Keyword Density Checker, estimate time on page with the Reading Time Calculator, and find more on the FHSEO Hub free SEO tools page.

Readability Checker FAQs

For most web content, a Flesch Reading Ease score of 60 or higher is a good target, which is roughly an 8th to 9th grade reading level. Content for a broad public audience can aim for 70 or above. Technical, academic and legal writing often scores lower, which is acceptable when readers expect specialist language.

A Flesch Reading Ease score of 60 means the text is “standard” or plain English, readable by most people with an 8th to 9th grade education, around 13 to 15 years old. It is a solid target for blogs, websites and business writing, balancing clarity with room for some longer or technical words.

Not directly. Google doesn’t use readability scores like Flesch Reading Ease as a ranking factor. Readable content can still help SEO indirectly, because clear, easy-to-scan writing keeps readers engaged, answers questions faster, and is easier for search engines and AI answer engines to understand and quote as answers.

Most blog posts work well at a grade 7 to 9 level, or a Flesch Reading Ease score of about 60 to 70. That suits busy readers skimming on phones. Posts for specialists can run higher, but simpler writing usually reads faster for everyone. Match the level to your audience and topic.

Each formula measures different features. Flesch scores use syllables per word, Coleman-Liau and ARI use letters per word, and Gunning Fog and SMOG focus on complex words. They were also built for different audiences and purposes. Compare several scores and look for the general range rather than relying on one number.