This free Readability Checker scores your writing as you type. Paste an article, an email, or a whole page of web copy. You get a Flesch Reading Ease score, a grade level, and four more classic formulas. Hard sentences light up right in the editor, so you know exactly what to fix. No signup, and nothing you paste leaves your browser.
What is a readability score?
A readability score estimates how easy your writing is to understand. The formulas only look at the text itself: word length, sentence length, and syllable counts. Two numbers get quoted most often. The Flesch Reading Ease score runs from 0 to 100, and higher means easier. The reading grade level is the U.S. school grade a reader needs to follow the text.
Any single formula can be quirky. So this checker runs six classic formulas at once, side by side. The big number at the top is your Flesch Reading Ease. The grade card averages the five grade-based formulas into one figure.
How to read your Flesch Reading Ease score
| Score | Difficulty | Typical reader |
|---|
| 90–100 | Very easy | 5th grader; comics, very simple copy |
| 80–89 | Easy | 6th grader; conversational consumer content |
| 70–79 | Fairly easy | 7th grader; most popular fiction |
| 60–69 | Plain English | 8th–9th grader; the sweet spot for web content |
| 50–59 | Fairly difficult | High-school senior; quality newspapers |
| 30–49 | Difficult | College student; academic and legal text |
| 0–29 | Very difficult | Graduate level; scientific papers |
For most web copy, aim for 60 or higher. That target is not about dumbing your writing down. The New York Times scores in the 50s. Most bestselling nonfiction lands between 60 and 80. Plain sentences simply let readers spend their attention on your ideas.
The six formulas this tool runs
Flesch Reading Ease
This is the most widely used readability test. It combines average sentence length with average syllables per word. Unlike the others, it gives an ease score, and higher means easier.
206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)
Flesch-Kincaid Grade Level
This takes the same two ingredients and rescales them to a U.S. school grade. The U.S. military adopted it for technical manuals. It is also the score built into Microsoft Word.
Gunning Fog Index
Fog works from sentence length plus the share of "complex" words. A complex word here means three or more syllables. Long words drag the index up fast, which makes it a handy jargon detector.
SMOG Index
SMOG is short for "Simple Measure of Gobbledygook." It predicts the grade needed for full comprehension, not partial understanding. That is why it usually reads a grade or two higher than the rest. Healthcare editors tend to prefer it. One caveat: SMOG was calibrated on samples of 30 or more sentences. Treat it as a rough estimate on anything shorter.
Coleman-Liau Index
Coleman-Liau counts characters per word instead of syllables. That makes it immune to syllable-counting quirks. It was designed for machine scoring, so its results are easy to reproduce.
Automated Readability Index (ARI)
ARI also relies on characters per word and words per sentence. It powers the sentence highlighting in this editor. Our Business Description Analyzer uses it too.
Sentence highlighting
Scores tell you a text is hard. Highlights tell you where. Each sentence gets scored on its own, and the difficult ones light up in the editor. A sentence of 14 words or more turns yellow when it needs a 10th-grade reader. It turns red at grade 14 or above. Sentences under 14 words never get flagged, even when they use long words. Short sentences stay easy to parse. The fix is almost always the same. Split the sentence in two, or swap a few long words for shorter ones.
How to improve a readability score
- Split long sentences. Every formula here punishes sentence length. If a sentence carries two ideas, give each its own sentence.
- Swap long words for short ones. Write "use", not "utilize". Write "help", not "facilitate". Fewer syllables per word lowers every score.
- Cut filler. Phrases like "in order to" and "due to the fact that" add length without adding meaning.
- Prefer active voice. "We tested the tool" is shorter and clearer than "the tool was tested by our team".
- Break up walls of text. Paragraph breaks barely move the formulas. They do decide whether anyone keeps reading.
Why readability matters for SEO
Google doesn't rank pages by Flesch score. Readability still drives the signals it does measure. Easy text keeps visitors on the page and earns more shares and links. Clear, plain answers also get quoted in featured snippets and AI summaries far more often. Hard pages send visitors straight back to the search results. That is a signal you don't want to send.
Frequently Asked Questions
What is a good readability score?
Aim for a Flesch Reading Ease of 60 or higher on general web content. Keep the grade level at 9 or below. Marketing copy can aim higher, around 70 or more. Technical documentation for a specialist audience can sit in the 40s and 50s.
What grade level should my writing be?
Around 8th or 9th grade for most audiences. Newspapers and bestselling books target that level. It also suits skimming, which is how nearly everyone reads online. Writing at a lower grade is not condescending. Even expert readers prefer plain text when they are moving fast.
Why do the six formulas give different numbers?
Each formula weighs the ingredients differently. Flesch-Kincaid leans on syllables. Coleman-Liau and ARI count characters. Gunning Fog and SMOG focus on words of three or more syllables. A spread of two or three grades between them is normal. So this tool shows all six, because the consensus matters more than any single number.
How accurate is the syllable counting?
The tool estimates syllables with the vowel-group heuristic most automated checkers use. The odd unusual word can be counted slightly off. Those errors average out across a document. The final scores match dedicated readability software within a fraction of a grade.
How much text can I check?
Up to 50,000 characters at once. That is roughly 8,000 words, or a very long blog post. Everything runs live in your browser. There are no daily limits and no word-count paywall.
Is my text stored anywhere when I use this tool?
No. All scoring runs in your browser using JavaScript. Nothing you type or paste is sent to our servers, stored, or logged.
Checking a short business description instead? Try our Business Description Analyzer. It adds length targets and keyword checks on top of the same engine. You will find more free tools on the SEO tools hub.