Test the Readability
Analyze your texts with the Flesch formula and other readability indexes.
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Flesch Reading Ease
Developed by Rudolf Flesch (1948) for English texts
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Flesch-Kincaid Grade Level
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Gunning Fog Index
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SMOG
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LIX Readability Index
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Text Statistics
Sentence Analysis
Sentences colored by readability: Easy Medium Hard
Readability Formulas
Flesch Reading Ease
RecommendedDeveloped by Rudolf Flesch (1948) for English texts
ASL = Average Sentence Length (words per sentence)
ASW = Average Syllables per Word
Other indexes
Flesch-Kincaid Grade Level
Indicates the US school grade level needed
Gunning Fog Index
Robert Gunning (1952) – based on complex words
SMOG
Simple Measure of Gobbledygook – recommended for healthcare
LIX Readability Index
Swedish formula, works across languages
More about readability indexes on Wikipedia
Interpretation Table
| Flesch Score | Difficulty | Example |
|---|---|---|
| 0–30 | Very hard | Academic papers |
| 30–50 | Hard | College textbooks |
| 50–60 | Fairly difficult | Quality newspapers |
| 60–70 | Medium | Tabloid newspapers |
| 70–80 | Easy | Advertising copy |
| 80–90 | Very easy | Comics, entertainment |
| 90–100 | Extremely easy | Elementary school level |
Frequently Asked Questions
What is the Flesch Index?
The Flesch Index (also Flesch Reading Ease) is a readability index that measures how easy a text is to understand. It was developed in 1948 by Rudolf Flesch and is based on average sentence length and average number of syllables per word. The higher the score (0-100), the easier the text is to read.
Which formula is used for English texts?
For English texts, the original Flesch Reading Ease formula is used: FRE = 206.835 - (1.015 × ASL) - (84.6 × ASW). This is the standard formula developed by Rudolf Flesch in 1948.
Are my texts stored?
No, never! All calculations happen directly in your browser. Your texts are never transmitted to or stored on any server. The analysis even works offline after the page has loaded once.
What Flesch score is ideal?
It depends on your target audience: General texts: 60-70 (Standard), Marketing/newsletters: 70-80 (Easy), Academic texts: 30-50 (Difficult), Children's texts: 80+ (Very easy).
Why are multiple indexes shown?
Different readability indexes measure different aspects. The Gunning Fog focuses on complex words, LIX works across languages, and SMOG is recommended for healthcare texts. Combining multiple indexes provides a more complete picture of text readability.
Can I share a link to an analysis?
Yes! You can pass text via the URL. Simply add ?text=Your+text+here to the URL. Short texts can be directly linked this way.
Tips for Readable Texts
Write short sentences
Keep your sentences short. Ideally no more than 15-20 words per sentence. One thought per sentence is enough.
Choose simple words
Use short, familiar words. Instead of "utilize" write "use". Instead of "subsequently" just write "then".
Use active voice
Write actively. Instead of "The report was written" use "We wrote the report". It's more direct and lively.
Use verbs instead of nouns
Avoid nominalizations. Instead of "The implementation of the analysis" use "We analyze". Verbs make texts come alive.
Explain or replace jargon
If you need technical terms, explain them briefly. Or find a simpler word instead.
Keep paragraphs short
Structure your text into short paragraphs. A paragraph should cover only one aspect. This makes reading easier.
Cut filler words
Remove unnecessary words like "basically", "actually", "in order to", or "for all intents and purposes". They bloat the text.
Read aloud
Read your text out loud. Where you stumble or need to catch your breath, the sentence is too long. That's where you can shorten or split.
Advantages
- Simple and fast calculation
- Objective measure of text comprehensibility
- Helps write clear, understandable texts
- Scientifically validated and widely used
- Useful for editors, copywriters, and translators
Disadvantages
- Does not consider content or context
- Technical terms are not specially evaluated
- Short texts may yield unreliable results
- Originally developed for English
- Not a substitute for human editing
Your data stays with you
All text analysis happens directly in your browser. Your text is never sent to or stored on any server.
This means:
- No data transmission to the internet
- No storage on external servers
- No cookies or tracking
- Fully usable offline (after first load)
You can safely analyze confidential texts or documents with personal data. All processing happens locally on your device.