Write Better: Online Readability Testing Tools Compared

There are a number of readability testing tools available on the web.

I was recently looking for a good online readability tool to use and as I was reviewing them I thought it would be helpful to write up my research. I found 12 tools worth checking out. My comparison of them is below.

I was especially interested to see how their results compared when analyzing the same text. I used the Gettysburg Address for my sample text (see "Conclusions" for some take aways).

I didn't comment on the UI of the tools as they were all easy to use and reasonably well presented. I haven't gone into detail on each of the readability tests either — it's all available on Wikipedia.

1. Edit Central

Summary

  • Readability ratings calculated using 6 formulas.
  • Color-coded scale makes interpreting readability scores easy to understand.
  • Highlights complex words of 3+ syllables.
  • Detailed content statistics, including average characters per word, syllables per word and words per sentence.
  • Easy to use interface.
  • Updates in real time without needing to resubmit (makes editing easy).
  • Cannot check a URL — only pasted text.
  • Provides demo texts for testing.

Sample Text Analysis

Readability:

  • Automated readability index: 12.2
  • Coleman-Liau index: 8.4
  • Flesch reading ease: 69.1
  • Flesch-Kincaid grade level: 10.3
  • Gunning fog index: 13.4
  • SMOG index: 10.3

Content Statistics:

  • 268 words
  • 18 complex words
  • 350 syllables
  • 10 sentences
  • 1.31 syllables per word

2. Tests Document Readability And Improve It

Summary

  • Check URL as well as pasted text.
  • Provides a list of sentences which it suggests rewriting to improve readability.
  • Results are clearly presented.

Sample Text Analysis

Readability:

  • ARI (Automated Readability Index): 12.22
  • Coleman Liau index: 8.40
  • Flesch Reading Ease: 60.94
  • Flesh-Kincaid Grade: 11.42
  • Gunning Fog index: 13.41
  • SMOG: 11.66

Content Statistics:

  • Words: 268
  • Sentences: 10
  • Syllables per word: 1.4
  • Words per sentence: 26.8

3. Juicy Studio Readability Test

Summary

  • Test a URL for readability but not pasted text.
  • Provides 3 readability formulas.
  • Shows number of words with 3 and 4+ syllables ('difficult' and 'really difficult' words).
  • Good place to start to learn about the different readability formulas.

Sample Text Analysis

Readability:

  • Flesch Reading Ease: 59.99
  • Flesch-Kincaid Grade: 11.55
  • Gunning Fog Index: 14.45

Content Statistics:

  • Sentences: 10
  • Words: 268
  • Words with 1 Syllable: 192
  • Words with 2 Syllables: 51
  • Words with 3 Syllables: 15
  • Words with 4 or more Syllables: 10
  • Syllables per Word: 1.41

4. Check Text Readability

Summary

  • Cannot check a URL.
  • Very limited statistics.
  • 3 readability formulas.

Sample Text Analysis

Readability:

  • Flesch Reading Ease: 46
  • Flesch-Kincaid Grade: 13
  • Gunning-Fog Index: 20

Content Statistics:

  • Syllables per word: 1.59
  • Words per sentence: 26.3

5. Readability Index Calculator

Summary

  • Provides readability formulas for multiple languages.
  • Only one readability formula for English text.
  • No text statistics.

Sample Text Analysis

Readability:

  • Flesch Reading Ease: 45
  • Flesch-Kincaid Grade: 14

6. Readability.info

Summary

  • Provides 7 readability formulas.
  • Can check Microsoft Word documents and URLs.
  • Unable to get document upload feature to work.
  • Cannot check pasted text.
  • Includes paragraph data in analysis.
  • Shows ratio of long to short sentences.

Sample Text Analysis

Readability:

  • ARI (Automated Readability Index): 11.0
  • Coleman-Liau Index: 8.0
  • Flesch Reading Ease: 73.3
  • Flesch-Kincaid Grade: 9.7
  • Gunning Fog Index: 12.8
  • Lix: 37.6 (school year 5)
  • SMOG-Grading: 9.5

Content Statistics:

  • Words: 267
  • Syllables per word: 1.26
  • Sentences: 10
  • Short sentences (at most 22 words): 60% (6)
  • Long sentences (at least 37 words): 10% (1)
  • Paragraphs: 5
  • Sentences per paragraph: 2.0
  • Passive sentences: 50% (5)
  • Longest sentence: 86 words

7. Text Content Analysis Tool

Summary

  • Provides very detailed text statistics, including 'hard' words (3+ syllables) and a word frequency cloud,
  • Cannot check a URL.
  • Free membership provides access to more advanced text analysis, including breakdown of words by length and graded analysis which highlights difficult words.

Sample Text Analysis

Readability:

  • Coleman-Liau Index: 9.52
  • Gunning Fog Index: 12.81
  • Lexical Density: 52.24

Content Statistics:

  • Words: 268
  • Different Words: 140
  • Sentences: 10
  • Words per Sentence: 26.80
  • Syllables per Word: 1.34
  • Hard Words: 19

8. SMOG Readability Calculator

Summary

  • Only provides one readability formula.
  • Cannot check a URL.
  • Resizes your browser window on pressing submit which is incredibly annoying.

Sample Text Analysis

Readability:

  • SMOG Grade: 10.75

Content Statistics:

  • Words: 268
  • Sentences: 10
  • Syllables per Word: 1.38
  • Syllables per Sentence: 37
  • Letters per Sentence: 115.2

9. Readability Analysis Tool

Summary

  • Cannot check a URL.
  • Provides 7 readability formulas.
  • Provides very helpful interpretation of readability results.
  • Calculates number of 'difficult' words (3+ syllables).

Sample Text Analysis

Readability:

  • Automated Readability Index: 13
  • Coleman-Liau: 10
  • Flesch Reading Ease: 53.2
  • Flesch-Kincaid grade level: 12
  • Gunning Fog Index: 17
  • Linsear Write: 5
  • SMOG-Grading: 13

Content Statistics:

  • Words: 263
  • Sentences: 10
  • Syllables per word: 1.5
  • Difficult words: 29

10. Topicalizer

Summary

  • Check a URL or pasted text.
  • Support for multiple languages (not tested).
  • Provides a very detailed statistical analysis including longest word and sentence, most frequent words and phrases, and paragraph-related data.
  • Provides 3 readability formulas.
  • Includes lexical density analysis.
  • Not clear how 'average readability' formula is calculated or on what scale it is based; therefore, it is not very useful.
  • Lots of statistical data makes the useful information harder to see.

Sample Text Analysis

Readability:

  • Automated Readability Index: 3.89
  • Coleman-Liau Index: 0.63
  • Gunning-Fog Index: 12.88
  • Average readability: 5.8

Content Statistics:

  • Words: 268
  • Distinct words: 108
  • Words per sentence: 24.36
  • Words per paragraph: 53.6
  • Paragraphs: 5
  • Sentences: 11
  • Sentences per paragraph: 2.2

11. TxReadability

Summary

  • Check readability in English, Spanish and Japanese.
  • Check a web page or pasted text.
  • Provides tables to help you interpret your readability scores.
  • Couldn't get readability interpretation functionality to work.
  • Provides a lot of background information on readability.

Sample Text Analysis

Readability:

  • Flesch Reading Ease: 50.27
  • Flesch-Kincaid Grade: 16.18

Content Statistics:

  • Words: 268
  • Sentences: 11
  • Syllables per 100 words: 1.37
  • Words per sentence: 40
  • 1 syllable words: 199
  • 2 syllable words: 45
  • 3+ syllable words: 24

12. The Blog Readability Test

Summary

  • Provides a nice looking graphic showing your readability level.
  • IMPORTANT: Be careful when using the HTML provided to embed the graphic as it includes an advertising link at the end. Just delete this link or save and upload the graphic to your server.
  • No information about what formula is used.
  • No text statistics.
  • Can only check a URL and not pasted text.
  • Could not get it to check any pages on my site (PHP problem?)

Sample Text Analysis

Not available.

Conclusions

I was surprised at the variation in the readability scores across the tools. For example, the Flesch reading ease score varied from 45 to 73.1 and the Flesch-Kincaid grade level from 9.7 to 16.18!

The tools couldn't even agree on whether there were 10 or 11 sentences. To be fair, one sentence is broken up by a colon, which may have caused some tools to treat it as two sentences.

I was also surprised that the number of 'difficult' or 'complex' words (3 or more syllables) varied from 18 to 29.

Based on this variability, the key to measuring the readability of your content on an ongoing basis seems to be to choose a tool that you are comfortable with and use it consistently, especially in multi-author environments. Switching between tools will cause differing results and confusion in comparing the readability of different content.

That being said, the tools provided differing levels of statistical analysis, so it might be worth using multiple tools to get a complete breakdown of your content (for example, to include paragraph-related as well as sentence-related data).

Posted on: December 26, 2007 | No comments

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