The Hemingway App charges $20 for readability scoring. Semrush and Ahrefs lock keyword density behind $100+/month plans.
The Word Counter at Ultimate Tools added both features free — paste any text and instantly see the Flesch-Kincaid Grade Level and top keyword density percentages.
Flesch-Kincaid Grade Level — What It Is and How It's Calculated
The FK Grade Level tells you roughly what US school grade a reader needs to comfortably understand your writing. Grade 8 = eighth grade reading level. Lower is more accessible.
The formula:
FK Grade = 0.39 × (words/sentences) + 11.8 × (syllables/words) − 15.59
In plain English: long sentences + complex words = high grade level. Short sentences + short words = low grade level.
| Grade | Label | Example |
|---|---|---|
| < 6 | Very Easy | Basic instructions, SMS |
| 6–8 | Easy | Blog posts, emails |
| 9–11 | Standard | News articles, reports |
| 12–14 | Difficult | Academic writing |
| 15+ | Very Difficult | Legal or technical docs |
For web content targeting a general audience, aim for Grade 6–8. For technical documentation, Grade 10–12 is acceptable.
Keyword Density — Why It Matters for SEO
Keyword density = (keyword count / total words) × 100
The tool shows the top 10 non-stop words by frequency, ranked by density percentage. This helps you:
- Spot overused words before publishing (keyword stuffing triggers Google penalties)
- Verify your target keyword appears with appropriate frequency (1–3% is generally healthy)
- Find unintentional keyword repetition that makes copy sound robotic
Stop words (the, a, is, of, and, etc.) are excluded from the density calculation so the results focus on meaningful terms.
How to Use the Word Counter
- Open the free word counter with readability
- Paste or type your text
- The tool instantly shows:
- Words, characters, sentences, paragraphs
- Read time and speak time
- FK Grade Level with a label (Very Easy → Very Difficult)
- Top 10 keywords with density % and raw count, shown as a bar chart
Everything updates in real time as you type. Nothing is sent to a server.
Practical Example
An article with 800 words, 45 sentences, and 1,200 syllables:
Words/sentences = 800/45 = 17.8 (average sentence length)
Syllables/words = 1200/800 = 1.5 (average word complexity)
FK Grade = 0.39 × 17.8 + 11.8 × 1.5 − 15.59
= 6.94 + 17.70 − 15.59
= 9.05 → Grade 9 (Standard)
To lower the grade: shorten sentences, replace multi-syllable words with simpler alternatives.
Who Uses This
- Content writers and bloggers — verify articles are readable for the target audience before publishing
- SEO teams — check keyword density without paying for an enterprise tool
- Students — ensure academic writing meets target complexity levels
- Marketers — make sure email subject lines and landing page copy are direct and clear
Hemingway App costs $20 one-time. Semrush keyword density analysis requires a subscription. This is completely free with no account.
Related Tools
- convert markdown to HTML online free — convert your article draft to HTML once readability and keyword density are optimised — live preview, one-click copy, no signup
- typing speed test with custom text free — paste the same article text and measure your WPM on real content — session history saves your last 10 results automatically
- free online case converter for text — convert headings and titles to Title Case, UPPER CASE, or sentence case after editing for readability
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