Each marker is one grade-level formula. The blue dot is their average. When the markers sit close together, the formulas agree.
Scores by formula
| Formula | Score | Reading level | What it looks at |
|---|
Text statistics
Showing your text with Markdown, HTML and links removed, exactly as it was scored.
Longest sentences
How to check the readability of your text
- Paste your text into the box, or open a .txt, .md, .html or .docx file. Nothing is uploaded. The file is read by your browser.
- Read the average grade level and the Flesch Reading Ease score at the top. The scale underneath shows where each formula lands, so you can see at a glance whether they agree.
- Set a target. Pick a formula and a grade (grade 8 is a common goal for general web content), and the checker tells you whether you hit it and by how much.
- Open Highlighted text to see which sentences run long and which words carry three or more syllables. Edit in the box above and every score updates as you type.
- Copy the report or download the scores and a sentence-by-sentence breakdown as CSV files.
What each readability score means
Every readability formula boils down to two ideas: long sentences are harder to follow, and long words are harder to read. The formulas differ in how they measure "long." Some count syllables, some count letters, and one counts only words with three or more syllables.
| Formula | How it's calculated | How to read it |
|---|---|---|
| Flesch Reading Ease | 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words) | 0 to 100. Higher is easier. 60 to 70 is plain English. |
| Flesch–Kincaid Grade Level | 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59 | A US school grade. 8 means an average eighth grader can follow it. |
| Gunning Fog Index | 0.4 × [(words ÷ sentences) + 100 × (complex words ÷ words)] | Years of schooling needed. Complex words have 3+ syllables, not counting proper nouns or -es, -ed and -ing endings. |
| SMOG Index | 1.0430 × √(words with 3+ syllables × 30 ÷ sentences) + 3.1291 | A grade level, widely used for health materials. Designed for samples of 30 sentences or more. |
| Coleman–Liau Index | 0.0588 × L − 0.296 × S − 15.8, where L is letters per 100 words and S is sentences per 100 words | A grade level based on letters instead of syllables, so it is not thrown off by syllable counting. |
| Automated Readability Index | 4.71 × (characters ÷ words) + 0.5 × (words ÷ sentences) − 21.43 | A grade level built from characters per word and words per sentence. |
The average grade level is the mean of the five grade-based formulas. It isn't an official score, but it smooths out the quirks of any single formula, which makes it a steadier number to track while you edit.
Flesch Reading Ease score chart
| Score | Difficulty | Approximate school level |
|---|---|---|
| 90–100 | Very easy | 5th grade |
| 80–90 | Easy | 6th grade |
| 70–80 | Fairly easy | 7th grade |
| 60–70 | Plain English | 8th and 9th grade |
| 50–60 | Fairly difficult | 10th to 12th grade |
| 30–50 | Difficult | College |
| 10–30 | Very difficult | College graduate |
| 0–10 | Extremely difficult | Professional |
What readability score should you aim for?
It depends on who is reading, but these are common targets:
- Blog posts, product pages and general web content: grade 7 to 9, or a Flesch Reading Ease of 60 to 70.
- Health information, government services and anything for the widest possible audience: grade 6 to 8. Plain-language guidelines often push for the low end of that range.
- Business, legal and technical writing for professionals: grade 10 to 12 is normal. Specialist terms raise the score, and that's fine when your readers know them.
- Academic writing: grade 13 and up is typical, though clearer is still better.
A lower score doesn't mean simpler ideas. It means fewer obstacles between the reader and the idea.
Why readability scores differ between checkers
If you run the same text through Microsoft Word, an SEO plugin and a few online checkers, you'll usually get different numbers. The formulas are the same. The counting isn't.
Syllables are estimated, not looked up. English spelling doesn't map cleanly to sound, so every tool uses rules to guess. This checker combines pronunciation rules (silent endings like "make" and "jumped," split vowels like "idea" and "radio," suffixes like "-ism" and "-ing") with a list of irregular words, and it was checked against a hand-verified list of more than 1,600 English words.
Sentence detection varies. A naive checker ends a sentence at every period, so "Dr. Smith arrived at 3.30 p.m." turns into three short sentences and the score looks easier than it is. This checker handles titles, initials, decimals, abbreviations and ellipses. Headings and list items without end punctuation count as separate sentences, instead of merging into the next paragraph.
Formatting gets in the way. Markdown symbols, HTML tags and URLs inflate word counts. With "Ignore Markdown, HTML and URLs" turned on, they're stripped before scoring, and code blocks and tables are skipped.
How to improve your readability score
- Split sentences over 25 words. Sentence length moves every formula, so this is usually the fastest win. The Sentence lengths tab lists your longest ones.
- Swap long words for short ones when the meaning holds. Use for utilize, help for facilitate, start for commence.
- Write in the active voice. "The team fixed the bug" is shorter and clearer than "The bug was fixed by the team."
- Keep one idea per paragraph. Short paragraphs are easier to scan, especially on phones.
- Use lists for steps and options. Readers find what they need without reading everything around it.
Frequently asked questions
Is my text uploaded or stored anywhere?
No. The analysis runs entirely in your browser, and files you open are read locally. Your text never leaves your device. The tool remembers your settings, like your target grade, but not your text.
What is a good Flesch–Kincaid grade level?
For most web content, aim for grade 8 or lower. That's readable for the large majority of adults. Health and public-service writing often targets grade 6 to 8. Professional and technical documents commonly land at grade 10 to 12.
What counts as a hard word?
A word with three or more syllables, following the Gunning Fog rule: proper nouns, acronyms and numbers don't count, and -es, -ed and -ing endings aren't counted as extra syllables. Hyphenated words count only if one of their parts is hard. Switch the setting to 4+ syllables to highlight only the longest words.
Why does SMOG show a warning for short text?
The SMOG formula was built for samples of 30 sentences. It adjusts shorter samples mathematically, but results on a paragraph or two are less reliable. Check longer passages when SMOG matters to you, as it often does for health materials.
Can I check a Word document or Google Doc?
Yes. Open a .docx file and the text is extracted in your browser. Images, comments and tracked deletions are ignored. For a Google Doc, choose File, then Download, then Microsoft Word (.docx), or copy the text and paste it in. For PDFs and older .doc files, copy and paste the text.
Does this work for languages other than English?
The formulas and syllable rules are calibrated for English. You can paste other languages, but the scores won't mean much.
Why doesn't my score match Microsoft Word or my SEO plugin?
Each tool counts syllables and sentences in its own way, so scores within about one grade of each other are normal. Larger gaps usually come from headings, lists or abbreviations being split into sentences differently. Pick one tool and use it consistently when you compare drafts.